feat: migrate tools to use parametersJsonSchema. (#5330)

17 files changed, 141 insertions, 423 deletions

diff --git a/packages/core/src/tools/edit.ts b/packages/core/src/tools/edit.ts
index 33323203..86641300 100644
--- a/packages/core/src/tools/edit.ts
+++ b/packages/core/src/tools/edit.ts
@@ -19,7 +19,6 @@ import {
   ToolResultDisplay,
 } from './tools.js';
 import { ToolErrorType } from './tool-error.js';
-import { Type } from '@google/genai';
 import { SchemaValidator } from '../utils/schemaValidator.js';
 import { makeRelative, shortenPath } from '../utils/paths.js';
 import { isNodeError } from '../utils/errors.js';
@@ -443,27 +442,27 @@ Expectation for required parameters:
           file_path: {
             description:
               "The absolute path to the file to modify. Must start with '/'.",
-            type: Type.STRING,
+            type: 'string',
           },
           old_string: {
             description:
               'The exact literal text to replace, preferably unescaped. For single replacements (default), include at least 3 lines of context BEFORE and AFTER the target text, matching whitespace and indentation precisely. For multiple replacements, specify expected_replacements parameter. If this string is not the exact literal text (i.e. you escaped it) or does not match exactly, the tool will fail.',
-            type: Type.STRING,
+            type: 'string',
           },
           new_string: {
             description:
               'The exact literal text to replace `old_string` with, preferably unescaped. Provide the EXACT text. Ensure the resulting code is correct and idiomatic.',
-            type: Type.STRING,
+            type: 'string',
           },
           expected_replacements: {
-            type: Type.NUMBER,
+            type: 'number',
             description:
               'Number of replacements expected. Defaults to 1 if not specified. Use when you want to replace multiple occurrences.',
             minimum: 1,
           },
         },
         required: ['file_path', 'old_string', 'new_string'],
-        type: Type.OBJECT,
+        type: 'object',
       },
     );
   }
@@ -474,7 +473,10 @@ Expectation for required parameters:
    * @returns Error message string or null if valid
    */
   validateToolParams(params: EditToolParams): string | null {
-    const errors = SchemaValidator.validate(this.schema.parameters, params);
+    const errors = SchemaValidator.validate(
+      this.schema.parametersJsonSchema,
+      params,
+    );
     if (errors) {
       return errors;
     }
diff --git a/packages/core/src/tools/glob.ts b/packages/core/src/tools/glob.ts
index df0cc348..eaedc20f 100644
--- a/packages/core/src/tools/glob.ts
+++ b/packages/core/src/tools/glob.ts
@@ -15,7 +15,6 @@ import {
   ToolInvocation,
   ToolResult,
 } from './tools.js';
-import { Type } from '@google/genai';
 import { shortenPath, makeRelative } from '../utils/paths.js';
 import { Config } from '../config/config.js';
 
@@ -255,26 +254,26 @@ export class GlobTool extends BaseDeclarativeTool<GlobToolParams, ToolResult> {
           pattern: {
             description:
               "The glob pattern to match against (e.g., '**/*.py', 'docs/*.md').",
-            type: Type.STRING,
+            type: 'string',
           },
           path: {
             description:
               'Optional: The absolute path to the directory to search within. If omitted, searches the root directory.',
-            type: Type.STRING,
+            type: 'string',
           },
           case_sensitive: {
             description:
               'Optional: Whether the search should be case-sensitive. Defaults to false.',
-            type: Type.BOOLEAN,
+            type: 'boolean',
           },
           respect_git_ignore: {
             description:
               'Optional: Whether to respect .gitignore patterns when finding files. Only available in git repositories. Defaults to true.',
-            type: Type.BOOLEAN,
+            type: 'boolean',
           },
         },
         required: ['pattern'],
-        type: Type.OBJECT,
+        type: 'object',
       },
     );
   }
@@ -283,7 +282,10 @@ export class GlobTool extends BaseDeclarativeTool<GlobToolParams, ToolResult> {
    * Validates the parameters for the tool.
    */
   validateToolParams(params: GlobToolParams): string | null {
-    const errors = SchemaValidator.validate(this.schema.parameters, params);
+    const errors = SchemaValidator.validate(
+      this.schema.parametersJsonSchema,
+      params,
+    );
     if (errors) {
       return errors;
     }
diff --git a/packages/core/src/tools/grep.ts b/packages/core/src/tools/grep.ts
index 8e2b84f1..f8ecdc9c 100644
--- a/packages/core/src/tools/grep.ts
+++ b/packages/core/src/tools/grep.ts
@@ -17,7 +17,6 @@ import {
   ToolInvocation,
   ToolResult,
 } from './tools.js';
-import { Type } from '@google/genai';
 import { SchemaValidator } from '../utils/schemaValidator.js';
 import { makeRelative, shortenPath } from '../utils/paths.js';
 import { getErrorMessage, isNodeError } from '../utils/errors.js';
@@ -550,21 +549,21 @@ export class GrepTool extends BaseDeclarativeTool<GrepToolParams, ToolResult> {
           pattern: {
             description:
               "The regular expression (regex) pattern to search for within file contents (e.g., 'function\\s+myFunction', 'import\\s+\\{.*\\}\\s+from\\s+.*').",
-            type: Type.STRING,
+            type: 'string',
           },
           path: {
             description:
               'Optional: The absolute path to the directory to search within. If omitted, searches the current working directory.',
-            type: Type.STRING,
+            type: 'string',
           },
           include: {
             description:
               "Optional: A glob pattern to filter which files are searched (e.g., '*.js', '*.{ts,tsx}', 'src/**'). If omitted, searches all files (respecting potential global ignores).",
-            type: Type.STRING,
+            type: 'string',
           },
         },
         required: ['pattern'],
-        type: Type.OBJECT,
+        type: 'object',
       },
     );
   }
@@ -616,7 +615,10 @@ export class GrepTool extends BaseDeclarativeTool<GrepToolParams, ToolResult> {
    * @returns An error message string if invalid, null otherwise
    */
   validateToolParams(params: GrepToolParams): string | null {
-    const errors = SchemaValidator.validate(this.schema.parameters, params);
+    const errors = SchemaValidator.validate(
+      this.schema.parametersJsonSchema,
+      params,
+    );
     if (errors) {
       return errors;
     }
diff --git a/packages/core/src/tools/ls.ts b/packages/core/src/tools/ls.ts
index 8490f18a..79820246 100644
--- a/packages/core/src/tools/ls.ts
+++ b/packages/core/src/tools/ls.ts
@@ -7,7 +7,6 @@
 import fs from 'fs';
 import path from 'path';
 import { BaseTool, Icon, ToolResult } from './tools.js';
-import { Type } from '@google/genai';
 import { SchemaValidator } from '../utils/schemaValidator.js';
 import { makeRelative, shortenPath } from '../utils/paths.js';
 import { Config, DEFAULT_FILE_FILTERING_OPTIONS } from '../config/config.js';
@@ -82,35 +81,35 @@ export class LSTool extends BaseTool<LSToolParams, ToolResult> {
           path: {
             description:
               'The absolute path to the directory to list (must be absolute, not relative)',
-            type: Type.STRING,
+            type: 'string',
           },
           ignore: {
             description: 'List of glob patterns to ignore',
             items: {
-              type: Type.STRING,
+              type: 'string',
             },
-            type: Type.ARRAY,
+            type: 'array',
           },
           file_filtering_options: {
             description:
               'Optional: Whether to respect ignore patterns from .gitignore or .geminiignore',
-            type: Type.OBJECT,
+            type: 'object',
             properties: {
               respect_git_ignore: {
                 description:
                   'Optional: Whether to respect .gitignore patterns when listing files. Only available in git repositories. Defaults to true.',
-                type: Type.BOOLEAN,
+                type: 'boolean',
               },
               respect_gemini_ignore: {
                 description:
                   'Optional: Whether to respect .geminiignore patterns when listing files. Defaults to true.',
-                type: Type.BOOLEAN,
+                type: 'boolean',
               },
             },
           },
         },
         required: ['path'],
-        type: Type.OBJECT,
+        type: 'object',
       },
     );
   }
@@ -121,7 +120,10 @@ export class LSTool extends BaseTool<LSToolParams, ToolResult> {
    * @returns An error message string if invalid, null otherwise
    */
   validateToolParams(params: LSToolParams): string | null {
-    const errors = SchemaValidator.validate(this.schema.parameters, params);
+    const errors = SchemaValidator.validate(
+      this.schema.parametersJsonSchema,
+      params,
+    );
     if (errors) {
       return errors;
     }
diff --git a/packages/core/src/tools/mcp-tool.ts b/packages/core/src/tools/mcp-tool.ts
index 3dd62e2b..4b9a9818 100644
--- a/packages/core/src/tools/mcp-tool.ts
+++ b/packages/core/src/tools/mcp-tool.ts
@@ -12,13 +12,7 @@ import {
   ToolMcpConfirmationDetails,
   Icon,
 } from './tools.js';
-import {
-  CallableTool,
-  Part,
-  FunctionCall,
-  FunctionDeclaration,
-  Type,
-} from '@google/genai';
+import { CallableTool, Part, FunctionCall } from '@google/genai';
 
 type ToolParams = Record<string, unknown>;
 
@@ -64,7 +58,7 @@ export class DiscoveredMCPTool extends BaseTool<ToolParams, ToolResult> {
     readonly serverName: string,
     readonly serverToolName: string,
     description: string,
-    readonly parameterSchemaJson: unknown,
+    readonly parameterSchema: unknown,
     readonly timeout?: number,
     readonly trust?: boolean,
     nameOverride?: string,
@@ -74,7 +68,7 @@ export class DiscoveredMCPTool extends BaseTool<ToolParams, ToolResult> {
       `${serverToolName} (${serverName} MCP Server)`,
       description,
       Icon.Hammer,
-      { type: Type.OBJECT }, // this is a dummy Schema for MCP, will be not be used to construct the FunctionDeclaration
+      parameterSchema,
       true, // isOutputMarkdown
       false, // canUpdateOutput
     );
@@ -86,25 +80,13 @@ export class DiscoveredMCPTool extends BaseTool<ToolParams, ToolResult> {
       this.serverName,
       this.serverToolName,
       this.description,
-      this.parameterSchemaJson,
+      this.parameterSchema,
       this.timeout,
       this.trust,
       `${this.serverName}__${this.serverToolName}`,
     );
   }
 
-  /**
-   * Overrides the base schema to use parametersJsonSchema when building
-   * FunctionDeclaration
-   */
-  override get schema(): FunctionDeclaration {
-    return {
-      name: this.name,
-      description: this.description,
-      parametersJsonSchema: this.parameterSchemaJson,
-    };
-  }
-
   async shouldConfirmExecute(
     _params: ToolParams,
     _abortSignal: AbortSignal,
diff --git a/packages/core/src/tools/memoryTool.test.ts b/packages/core/src/tools/memoryTool.test.ts
index 5a9b5f26..2a5c4c39 100644
--- a/packages/core/src/tools/memoryTool.test.ts
+++ b/packages/core/src/tools/memoryTool.test.ts
@@ -203,7 +203,17 @@ describe('MemoryTool', () => {
       );
       expect(memoryTool.schema).toBeDefined();
       expect(memoryTool.schema.name).toBe('save_memory');
-      expect(memoryTool.schema.parameters?.properties?.fact).toBeDefined();
+      expect(memoryTool.schema.parametersJsonSchema).toStrictEqual({
+        type: 'object',
+        properties: {
+          fact: {
+            type: 'string',
+            description:
+              'The specific fact or piece of information to remember. Should be a clear, self-contained statement.',
+          },
+        },
+        required: ['fact'],
+      });
     });
 
     it('should call performAddMemoryEntry with correct parameters and return success', async () => {
diff --git a/packages/core/src/tools/memoryTool.ts b/packages/core/src/tools/memoryTool.ts
index f3bf315b..f0c95b6a 100644
--- a/packages/core/src/tools/memoryTool.ts
+++ b/packages/core/src/tools/memoryTool.ts
@@ -11,7 +11,7 @@ import {
   ToolConfirmationOutcome,
   Icon,
 } from './tools.js';
-import { FunctionDeclaration, Type } from '@google/genai';
+import { FunctionDeclaration } from '@google/genai';
 import * as fs from 'fs/promises';
 import * as path from 'path';
 import { homedir } from 'os';
@@ -24,11 +24,11 @@ const memoryToolSchemaData: FunctionDeclaration = {
   name: 'save_memory',
   description:
     'Saves a specific piece of information or fact to your long-term memory. Use this when the user explicitly asks you to remember something, or when they state a clear, concise fact that seems important to retain for future interactions.',
-  parameters: {
-    type: Type.OBJECT,
+  parametersJsonSchema: {
+    type: 'object',
     properties: {
       fact: {
-        type: Type.STRING,
+        type: 'string',
         description:
           'The specific fact or piece of information to remember. Should be a clear, self-contained statement.',
       },
@@ -123,7 +123,7 @@ export class MemoryTool
       'Save Memory',
       memoryToolDescription,
       Icon.LightBulb,
-      memoryToolSchemaData.parameters as Record<string, unknown>,
+      memoryToolSchemaData.parametersJsonSchema as Record<string, unknown>,
     );
   }
 
diff --git a/packages/core/src/tools/read-file.ts b/packages/core/src/tools/read-file.ts
index 2ab50282..0c040b66 100644
--- a/packages/core/src/tools/read-file.ts
+++ b/packages/core/src/tools/read-file.ts
@@ -16,7 +16,7 @@ import {
   ToolResult,
 } from './tools.js';
 import { ToolErrorType } from './tool-error.js';
-import { PartUnion, Type } from '@google/genai';
+import { PartUnion } from '@google/genai';
 import {
   processSingleFileContent,
   getSpecificMimeType,
@@ -179,27 +179,30 @@ export class ReadFileTool extends BaseDeclarativeTool<
           absolute_path: {
             description:
               "The absolute path to the file to read (e.g., '/home/user/project/file.txt'). Relative paths are not supported. You must provide an absolute path.",
-            type: Type.STRING,
+            type: 'string',
           },
           offset: {
             description:
               "Optional: For text files, the 0-based line number to start reading from. Requires 'limit' to be set. Use for paginating through large files.",
-            type: Type.NUMBER,
+            type: 'number',
           },
           limit: {
             description:
               "Optional: For text files, maximum number of lines to read. Use with 'offset' to paginate through large files. If omitted, reads the entire file (if feasible, up to a default limit).",
-            type: Type.NUMBER,
+            type: 'number',
           },
         },
         required: ['absolute_path'],
-        type: Type.OBJECT,
+        type: 'object',
       },
     );
   }
 
   protected validateToolParams(params: ReadFileToolParams): string | null {
-    const errors = SchemaValidator.validate(this.schema.parameters, params);
+    const errors = SchemaValidator.validate(
+      this.schema.parametersJsonSchema,
+      params,
+    );
     if (errors) {
       return errors;
     }
diff --git a/packages/core/src/tools/read-many-files.ts b/packages/core/src/tools/read-many-files.ts
index a380ea91..1c92b4f3 100644
--- a/packages/core/src/tools/read-many-files.ts
+++ b/packages/core/src/tools/read-many-files.ts
@@ -16,7 +16,7 @@ import {
   DEFAULT_ENCODING,
   getSpecificMimeType,
 } from '../utils/fileUtils.js';
-import { PartListUnion, Schema, Type } from '@google/genai';
+import { PartListUnion } from '@google/genai';
 import { Config, DEFAULT_FILE_FILTERING_OPTIONS } from '../config/config.js';
 import {
   recordFileOperationMetric,
@@ -150,47 +150,47 @@ export class ReadManyFilesTool extends BaseTool<
   static readonly Name: string = 'read_many_files';
 
   constructor(private config: Config) {
-    const parameterSchema: Schema = {
-      type: Type.OBJECT,
+    const parameterSchema = {
+      type: 'object',
       properties: {
         paths: {
-          type: Type.ARRAY,
+          type: 'array',
           items: {
-            type: Type.STRING,
-            minLength: '1',
+            type: 'string',
+            minLength: 1,
           },
-          minItems: '1',
+          minItems: 1,
           description:
             "Required. An array of glob patterns or paths relative to the tool's target directory. Examples: ['src/**/*.ts'], ['README.md', 'docs/']",
         },
         include: {
-          type: Type.ARRAY,
+          type: 'array',
           items: {
-            type: Type.STRING,
-            minLength: '1',
+            type: 'string',
+            minLength: 1,
           },
           description:
             'Optional. Additional glob patterns to include. These are merged with `paths`. Example: ["*.test.ts"] to specifically add test files if they were broadly excluded.',
           default: [],
         },
         exclude: {
-          type: Type.ARRAY,
+          type: 'array',
           items: {
-            type: Type.STRING,
-            minLength: '1',
+            type: 'string',
+            minLength: 1,
           },
           description:
             'Optional. Glob patterns for files/directories to exclude. Added to default excludes if useDefaultExcludes is true. Example: ["**/*.log", "temp/"]',
           default: [],
         },
         recursive: {
-          type: Type.BOOLEAN,
+          type: 'boolean',
           description:
             'Optional. Whether to search recursively (primarily controlled by `**` in glob patterns). Defaults to true.',
           default: true,
         },
         useDefaultExcludes: {
-          type: Type.BOOLEAN,
+          type: 'boolean',
           description:
             'Optional. Whether to apply a list of default exclusion patterns (e.g., node_modules, .git, binary files). Defaults to true.',
           default: true,
@@ -198,17 +198,17 @@ export class ReadManyFilesTool extends BaseTool<
         file_filtering_options: {
           description:
             'Whether to respect ignore patterns from .gitignore or .geminiignore',
-          type: Type.OBJECT,
+          type: 'object',
           properties: {
             respect_git_ignore: {
               description:
                 'Optional: Whether to respect .gitignore patterns when listing files. Only available in git repositories. Defaults to true.',
-              type: Type.BOOLEAN,
+              type: 'boolean',
             },
             respect_gemini_ignore: {
               description:
                 'Optional: Whether to respect .geminiignore patterns when listing files. Defaults to true.',
-              type: Type.BOOLEAN,
+              type: 'boolean',
             },
           },
         },
@@ -235,7 +235,10 @@ Use this tool when the user's query implies needing the content of several files
   }
 
   validateParams(params: ReadManyFilesParams): string | null {
-    const errors = SchemaValidator.validate(this.schema.parameters, params);
+    const errors = SchemaValidator.validate(
+      this.schema.parametersJsonSchema,
+      params,
+    );
     if (errors) {
       return errors;
     }
diff --git a/packages/core/src/tools/shell.ts b/packages/core/src/tools/shell.ts
index 6106c0cd..de9b7c2f 100644
--- a/packages/core/src/tools/shell.ts
+++ b/packages/core/src/tools/shell.ts
@@ -18,7 +18,6 @@ import {
   Icon,
 } from './tools.js';
 import { ToolErrorType } from './tool-error.js';
-import { Type } from '@google/genai';
 import { SchemaValidator } from '../utils/schemaValidator.js';
 import { getErrorMessage } from '../utils/errors.js';
 import { summarizeToolOutput } from '../utils/summarizer.js';
@@ -64,19 +63,19 @@ export class ShellTool extends BaseTool<ShellToolParams, ToolResult> {
       Process Group PGID: Process group started or \`(none)\``,
       Icon.Terminal,
       {
-        type: Type.OBJECT,
+        type: 'object',
         properties: {
           command: {
-            type: Type.STRING,
+            type: 'string',
             description: 'Exact bash command to execute as `bash -c <command>`',
           },
           description: {
-            type: Type.STRING,
+            type: 'string',
             description:
               'Brief description of the command for the user. Be specific and concise. Ideally a single sentence. Can be up to 3 sentences for clarity. No line breaks.',
           },
           directory: {
-            type: Type.STRING,
+            type: 'string',
             description:
               '(OPTIONAL) Directory to run the command in, if not the project root directory. Must be relative to the project root directory and must already exist.',
           },
@@ -113,7 +112,10 @@ export class ShellTool extends BaseTool<ShellToolParams, ToolResult> {
       }
       return commandCheck.reason;
     }
-    const errors = SchemaValidator.validate(this.schema.parameters, params);
+    const errors = SchemaValidator.validate(
+      this.schema.parametersJsonSchema,
+      params,
+    );
     if (errors) {
       return errors;
     }
diff --git a/packages/core/src/tools/tool-registry.test.ts b/packages/core/src/tools/tool-registry.test.ts
index d8e536b7..13dff08c 100644
--- a/packages/core/src/tools/tool-registry.test.ts
+++ b/packages/core/src/tools/tool-registry.test.ts
@@ -15,19 +15,9 @@ import {
   Mocked,
 } from 'vitest';
 import { Config, ConfigParameters, ApprovalMode } from '../config/config.js';
-import {
-  ToolRegistry,
-  DiscoveredTool,
-  sanitizeParameters,
-} from './tool-registry.js';
+import { ToolRegistry, DiscoveredTool } from './tool-registry.js';
 import { DiscoveredMCPTool } from './mcp-tool.js';
-import {
-  FunctionDeclaration,
-  CallableTool,
-  mcpToTool,
-  Type,
-  Schema,
-} from '@google/genai';
+import { FunctionDeclaration, CallableTool, mcpToTool } from '@google/genai';
 import { spawn } from 'node:child_process';
 
 import fs from 'node:fs';
@@ -254,18 +244,18 @@ describe('ToolRegistry', () => {
   });
 
   describe('discoverTools', () => {
-    it('should sanitize tool parameters during discovery from command', async () => {
+    it('should will preserve tool parametersJsonSchema during discovery from command', async () => {
       const discoveryCommand = 'my-discovery-command';
       mockConfigGetToolDiscoveryCommand.mockReturnValue(discoveryCommand);
 
       const unsanitizedToolDeclaration: FunctionDeclaration = {
         name: 'tool-with-bad-format',
         description: 'A tool with an invalid format property',
-        parameters: {
-          type: Type.OBJECT,
+        parametersJsonSchema: {
+          type: 'object',
           properties: {
             some_string: {
-              type: Type.STRING,
+              type: 'string',
               format: 'uuid', // This is an unsupported format
             },
           },
@@ -308,12 +298,16 @@ describe('ToolRegistry', () => {
       expect(discoveredTool).toBeDefined();
 
       const registeredParams = (discoveredTool as DiscoveredTool).schema
-        .parameters as Schema;
-      expect(registeredParams.properties?.['some_string']).toBeDefined();
-      expect(registeredParams.properties?.['some_string']).toHaveProperty(
-        'format',
-        undefined,
-      );
+        .parametersJsonSchema;
+      expect(registeredParams).toStrictEqual({
+        type: 'object',
+        properties: {
+          some_string: {
+            type: 'string',
+            format: 'uuid',
+          },
+        },
+      });
     });
 
     it('should discover tools using MCP servers defined in getMcpServers', async () => {
@@ -365,187 +359,3 @@ describe('ToolRegistry', () => {
     });
   });
 });
-
-describe('sanitizeParameters', () => {
-  it('should remove default when anyOf is present', () => {
-    const schema: Schema = {
-      anyOf: [{ type: Type.STRING }, { type: Type.NUMBER }],
-      default: 'hello',
-    };
-    sanitizeParameters(schema);
-    expect(schema.default).toBeUndefined();
-  });
-
-  it('should recursively sanitize items in anyOf', () => {
-    const schema: Schema = {
-      anyOf: [
-        {
-          anyOf: [{ type: Type.STRING }],
-          default: 'world',
-        },
-        { type: Type.NUMBER },
-      ],
-    };
-    sanitizeParameters(schema);
-    expect(schema.anyOf![0].default).toBeUndefined();
-  });
-
-  it('should recursively sanitize items in items', () => {
-    const schema: Schema = {
-      items: {
-        anyOf: [{ type: Type.STRING }],
-        default: 'world',
-      },
-    };
-    sanitizeParameters(schema);
-    expect(schema.items!.default).toBeUndefined();
-  });
-
-  it('should recursively sanitize items in properties', () => {
-    const schema: Schema = {
-      properties: {
-        prop1: {
-          anyOf: [{ type: Type.STRING }],
-          default: 'world',
-        },
-      },
-    };
-    sanitizeParameters(schema);
-    expect(schema.properties!.prop1.default).toBeUndefined();
-  });
-
-  it('should handle complex nested schemas', () => {
-    const schema: Schema = {
-      properties: {
-        prop1: {
-          items: {
-            anyOf: [{ type: Type.STRING }],
-            default: 'world',
-          },
-        },
-        prop2: {
-          anyOf: [
-            {
-              properties: {
-                nestedProp: {
-                  anyOf: [{ type: Type.NUMBER }],
-                  default: 123,
-                },
-              },
-            },
-          ],
-        },
-      },
-    };
-    sanitizeParameters(schema);
-    expect(schema.properties!.prop1.items!.default).toBeUndefined();
-    const nestedProp =
-      schema.properties!.prop2.anyOf![0].properties!.nestedProp;
-    expect(nestedProp?.default).toBeUndefined();
-  });
-
-  it('should remove unsupported format from a simple string property', () => {
-    const schema: Schema = {
-      type: Type.OBJECT,
-      properties: {
-        name: { type: Type.STRING },
-        id: { type: Type.STRING, format: 'uuid' },
-      },
-    };
-    sanitizeParameters(schema);
-    expect(schema.properties?.['id']).toHaveProperty('format', undefined);
-    expect(schema.properties?.['name']).not.toHaveProperty('format');
-  });
-
-  it('should NOT remove supported format values', () => {
-    const schema: Schema = {
-      type: Type.OBJECT,
-      properties: {
-        date: { type: Type.STRING, format: 'date-time' },
-        role: {
-          type: Type.STRING,
-          format: 'enum',
-          enum: ['admin', 'user'],
-        },
-      },
-    };
-    const originalSchema = JSON.parse(JSON.stringify(schema));
-    sanitizeParameters(schema);
-    expect(schema).toEqual(originalSchema);
-  });
-
-  it('should handle arrays of objects', () => {
-    const schema: Schema = {
-      type: Type.OBJECT,
-      properties: {
-        items: {
-          type: Type.ARRAY,
-          items: {
-            type: Type.OBJECT,
-            properties: {
-              itemId: { type: Type.STRING, format: 'uuid' },
-            },
-          },
-        },
-      },
-    };
-    sanitizeParameters(schema);
-    expect(
-      (schema.properties?.['items']?.items as Schema)?.properties?.['itemId'],
-    ).toHaveProperty('format', undefined);
-  });
-
-  it('should handle schemas with no properties to sanitize', () => {
-    const schema: Schema = {
-      type: Type.OBJECT,
-      properties: {
-        count: { type: Type.NUMBER },
-        isActive: { type: Type.BOOLEAN },
-      },
-    };
-    const originalSchema = JSON.parse(JSON.stringify(schema));
-    sanitizeParameters(schema);
-    expect(schema).toEqual(originalSchema);
-  });
-
-  it('should not crash on an empty or undefined schema', () => {
-    expect(() => sanitizeParameters({})).not.toThrow();
-    expect(() => sanitizeParameters(undefined)).not.toThrow();
-  });
-
-  it('should handle complex nested schemas with cycles', () => {
-    const userNode: any = {
-      type: Type.OBJECT,
-      properties: {
-        id: { type: Type.STRING, format: 'uuid' },
-        name: { type: Type.STRING },
-        manager: {
-          type: Type.OBJECT,
-          properties: {
-            id: { type: Type.STRING, format: 'uuid' },
-          },
-        },
-      },
-    };
-    userNode.properties.reports = {
-      type: Type.ARRAY,
-      items: userNode,
-    };
-
-    const schema: Schema = {
-      type: Type.OBJECT,
-      properties: {
-        ceo: userNode,
-      },
-    };
-
-    expect(() => sanitizeParameters(schema)).not.toThrow();
-    expect(schema.properties?.['ceo']?.properties?.['id']).toHaveProperty(
-      'format',
-      undefined,
-    );
-    expect(
-      schema.properties?.['ceo']?.properties?.['manager']?.properties?.['id'],
-    ).toHaveProperty('format', undefined);
-  });
-});
diff --git a/packages/core/src/tools/tool-registry.ts b/packages/core/src/tools/tool-registry.ts
index 70226052..17d324b3 100644
--- a/packages/core/src/tools/tool-registry.ts
+++ b/packages/core/src/tools/tool-registry.ts
@@ -4,7 +4,7 @@
  * SPDX-License-Identifier: Apache-2.0
  */
 
-import { FunctionDeclaration, Schema, Type } from '@google/genai';
+import { FunctionDeclaration } from '@google/genai';
 import { AnyDeclarativeTool, Icon, ToolResult, BaseTool } from './tools.js';
 import { Config } from '../config/config.js';
 import { spawn } from 'node:child_process';
@@ -331,14 +331,12 @@ export class ToolRegistry {
           console.warn('Discovered a tool with no name. Skipping.');
           continue;
         }
-        // Sanitize the parameters before registering the tool.
         const parameters =
-          func.parameters &&
-          typeof func.parameters === 'object' &&
-          !Array.isArray(func.parameters)
-            ? (func.parameters as Schema)
+          func.parametersJsonSchema &&
+          typeof func.parametersJsonSchema === 'object' &&
+          !Array.isArray(func.parametersJsonSchema)
+            ? func.parametersJsonSchema
             : {};
-        sanitizeParameters(parameters);
         this.registerTool(
           new DiscoveredTool(
             this.config,
@@ -413,75 +411,3 @@ export class ToolRegistry {
     return this.tools.get(name);
   }
 }
-
-/**
- * Sanitizes a schema object in-place to ensure compatibility with the Gemini API.
- *
- * NOTE: This function mutates the passed schema object.
- *
- * It performs the following actions:
- * - Removes the `default` property when `anyOf` is present.
- * - Removes unsupported `format` values from string properties, keeping only 'enum' and 'date-time'.
- * - Recursively sanitizes nested schemas within `anyOf`, `items`, and `properties`.
- * - Handles circular references within the schema to prevent infinite loops.
- *
- * @param schema The schema object to sanitize. It will be modified directly.
- */
-export function sanitizeParameters(schema?: Schema) {
-  _sanitizeParameters(schema, new Set<Schema>());
-}
-
-/**
- * Internal recursive implementation for sanitizeParameters.
- * @param schema The schema object to sanitize.
- * @param visited A set used to track visited schema objects during recursion.
- */
-function _sanitizeParameters(schema: Schema | undefined, visited: Set<Schema>) {
-  if (!schema || visited.has(schema)) {
-    return;
-  }
-  visited.add(schema);
-
-  if (schema.anyOf) {
-    // Vertex AI gets confused if both anyOf and default are set.
-    schema.default = undefined;
-    for (const item of schema.anyOf) {
-      if (typeof item !== 'boolean') {
-        _sanitizeParameters(item, visited);
-      }
-    }
-  }
-  if (schema.items && typeof schema.items !== 'boolean') {
-    _sanitizeParameters(schema.items, visited);
-  }
-  if (schema.properties) {
-    for (const item of Object.values(schema.properties)) {
-      if (typeof item !== 'boolean') {
-        _sanitizeParameters(item, visited);
-      }
-    }
-  }
-
-  // Handle enum values - Gemini API only allows enum for STRING type
-  if (schema.enum && Array.isArray(schema.enum)) {
-    if (schema.type !== Type.STRING) {
-      // If enum is present but type is not STRING, convert type to STRING
-      schema.type = Type.STRING;
-    }
-    // Filter out null and undefined values, then convert remaining values to strings for Gemini API compatibility
-    schema.enum = schema.enum
-      .filter((value: unknown) => value !== null && value !== undefined)
-      .map((value: unknown) => String(value));
-  }
-
-  // Vertex AI only supports 'enum' and 'date-time' for STRING format.
-  if (schema.type === Type.STRING) {
-    if (
-      schema.format &&
-      schema.format !== 'enum' &&
-      schema.format !== 'date-time'
-    ) {
-      schema.format = undefined;
-    }
-  }
-}
diff --git a/packages/core/src/tools/tools.ts b/packages/core/src/tools/tools.ts
index 8e064973..4b13174c 100644
--- a/packages/core/src/tools/tools.ts
+++ b/packages/core/src/tools/tools.ts
@@ -4,7 +4,7 @@
  * SPDX-License-Identifier: Apache-2.0
  */
 
-import { FunctionDeclaration, PartListUnion, Schema } from '@google/genai';
+import { FunctionDeclaration, PartListUnion } from '@google/genai';
 import { ToolErrorType } from './tool-error.js';
 import { DiffUpdateResult } from '../ide/ideContext.js';
 
@@ -186,7 +186,7 @@ export abstract class DeclarativeTool<
     readonly displayName: string,
     readonly description: string,
     readonly icon: Icon,
-    readonly parameterSchema: Schema,
+    readonly parameterSchema: unknown,
     readonly isOutputMarkdown: boolean = true,
     readonly canUpdateOutput: boolean = false,
   ) {}
@@ -195,7 +195,7 @@ export abstract class DeclarativeTool<
     return {
       name: this.name,
       description: this.description,
-      parameters: this.parameterSchema,
+      parametersJsonSchema: this.parameterSchema,
     };
   }
 
@@ -281,14 +281,14 @@ export abstract class BaseTool<
    * @param description Description of what the tool does
    * @param isOutputMarkdown Whether the tool's output should be rendered as markdown
    * @param canUpdateOutput Whether the tool supports live (streaming) output
-   * @param parameterSchema Open API 3.0 Schema defining the parameters
+   * @param parameterSchema JSON Schema defining the parameters
    */
   constructor(
     readonly name: string,
     readonly displayName: string,
     readonly description: string,
     readonly icon: Icon,
-    readonly parameterSchema: Schema,
+    readonly parameterSchema: unknown,
     readonly isOutputMarkdown: boolean = true,
     readonly canUpdateOutput: boolean = false,
   ) {
diff --git a/packages/core/src/tools/web-fetch.ts b/packages/core/src/tools/web-fetch.ts
index c96cae6c..6733c38d 100644
--- a/packages/core/src/tools/web-fetch.ts
+++ b/packages/core/src/tools/web-fetch.ts
@@ -12,7 +12,6 @@ import {
   ToolConfirmationOutcome,
   Icon,
 } from './tools.js';
-import { Type } from '@google/genai';
 import { getErrorMessage } from '../utils/errors.js';
 import { Config, ApprovalMode } from '../config/config.js';
 import { getResponseText } from '../utils/generateContentResponseUtilities.js';
@@ -77,11 +76,11 @@ export class WebFetchTool extends BaseTool<WebFetchToolParams, ToolResult> {
           prompt: {
             description:
               'A comprehensive prompt that includes the URL(s) (up to 20) to fetch and specific instructions on how to process their content (e.g., "Summarize https://example.com/article and extract key points from https://another.com/data"). Must contain as least one URL starting with http:// or https://.',
-            type: Type.STRING,
+            type: 'string',
           },
         },
         required: ['prompt'],
-        type: Type.OBJECT,
+        type: 'object',
       },
     );
     const proxy = config.getProxy();
@@ -156,7 +155,10 @@ ${textContent}
   }
 
   validateParams(params: WebFetchToolParams): string | null {
-    const errors = SchemaValidator.validate(this.schema.parameters, params);
+    const errors = SchemaValidator.validate(
+      this.schema.parametersJsonSchema,
+      params,
+    );
     if (errors) {
       return errors;
     }
diff --git a/packages/core/src/tools/web-search.ts b/packages/core/src/tools/web-search.ts
index 480cc7e7..8fe29967 100644
--- a/packages/core/src/tools/web-search.ts
+++ b/packages/core/src/tools/web-search.ts
@@ -89,7 +89,10 @@ export class WebSearchTool extends BaseTool<
    * @returns An error message string if validation fails, null if valid
    */
   validateParams(params: WebSearchToolParams): string | null {
-    const errors = SchemaValidator.validate(this.schema.parameters, params);
+    const errors = SchemaValidator.validate(
+      this.schema.parametersJsonSchema,
+      params,
+    );
     if (errors) {
       return errors;
     }
diff --git a/packages/core/src/tools/write-file.ts b/packages/core/src/tools/write-file.ts
index b018d653..5cdba419 100644
--- a/packages/core/src/tools/write-file.ts
+++ b/packages/core/src/tools/write-file.ts
@@ -18,7 +18,6 @@ import {
   Icon,
 } from './tools.js';
 import { ToolErrorType } from './tool-error.js';
-import { Type } from '@google/genai';
 import { SchemaValidator } from '../utils/schemaValidator.js';
 import { makeRelative, shortenPath } from '../utils/paths.js';
 import { getErrorMessage, isNodeError } from '../utils/errors.js';
@@ -89,21 +88,24 @@ export class WriteFileTool
           file_path: {
             description:
               "The absolute path to the file to write to (e.g., '/home/user/project/file.txt'). Relative paths are not supported.",
-            type: Type.STRING,
+            type: 'string',
           },
           content: {
             description: 'The content to write to the file.',
-            type: Type.STRING,
+            type: 'string',
           },
         },
         required: ['file_path', 'content'],
-        type: Type.OBJECT,
+        type: 'object',
       },
     );
   }
 
   validateToolParams(params: WriteFileToolParams): string | null {
-    const errors = SchemaValidator.validate(this.schema.parameters, params);
+    const errors = SchemaValidator.validate(
+      this.schema.parametersJsonSchema,
+      params,
+    );
     if (errors) {
       return errors;
     }
diff --git a/packages/core/src/utils/schemaValidator.ts b/packages/core/src/utils/schemaValidator.ts
index cb025774..f397c0b1 100644
--- a/packages/core/src/utils/schemaValidator.ts
+++ b/packages/core/src/utils/schemaValidator.ts
@@ -4,7 +4,6 @@
  * SPDX-License-Identifier: Apache-2.0
  */
 
-import { Schema } from '@google/genai';
 import AjvPkg from 'ajv';
 // Ajv's ESM/CJS interop: use 'any' for compatibility as recommended by Ajv docs
 // eslint-disable-next-line @typescript-eslint/no-explicit-any
@@ -19,50 +18,18 @@ export class SchemaValidator {
    * Returns null if the data confroms to the schema described by schema (or if schema
    *  is null). Otherwise, returns a string describing the error.
    */
-  static validate(schema: Schema | undefined, data: unknown): string | null {
+  static validate(schema: unknown | undefined, data: unknown): string | null {
     if (!schema) {
       return null;
     }
     if (typeof data !== 'object' || data === null) {
       return 'Value of params must be an object';
     }
-    const validate = ajValidator.compile(this.toObjectSchema(schema));
+    const validate = ajValidator.compile(schema);
     const valid = validate(data);
     if (!valid && validate.errors) {
       return ajValidator.errorsText(validate.errors, { dataVar: 'params' });
     }
     return null;
   }
-
-  /**
-   * Converts @google/genai's Schema to an object compatible with avj.
-   * This is necessary because it represents Types as an Enum (with
-   * UPPERCASE values) and minItems and minLength as strings, when they should be numbers.
-   */
-  private static toObjectSchema(schema: Schema): object {
-    const newSchema: Record<string, unknown> = { ...schema };
-    if (newSchema.anyOf && Array.isArray(newSchema.anyOf)) {
-      newSchema.anyOf = newSchema.anyOf.map((v) => this.toObjectSchema(v));
-    }
-    if (newSchema.items) {
-      newSchema.items = this.toObjectSchema(newSchema.items);
-    }
-    if (newSchema.properties && typeof newSchema.properties === 'object') {
-      const newProperties: Record<string, unknown> = {};
-      for (const [key, value] of Object.entries(newSchema.properties)) {
-        newProperties[key] = this.toObjectSchema(value as Schema);
-      }
-      newSchema.properties = newProperties;
-    }
-    if (newSchema.type) {
-      newSchema.type = String(newSchema.type).toLowerCase();
-    }
-    if (newSchema.minItems) {
-      newSchema.minItems = Number(newSchema.minItems);
-    }
-    if (newSchema.minLength) {
-      newSchema.minLength = Number(newSchema.minLength);
-    }
-    return newSchema;
-  }
 }