1 files changed, 77 insertions, 38 deletions

diff --git a/packages/core/src/tools/mcp-tool.ts b/packages/core/src/tools/mcp-tool.ts
index 59f83db3..01a8d75c 100644
--- a/packages/core/src/tools/mcp-tool.ts
+++ b/packages/core/src/tools/mcp-tool.ts
@@ -5,14 +5,16 @@
  */
 
 import {
-  BaseTool,
-  ToolResult,
+  BaseDeclarativeTool,
+  BaseToolInvocation,
+  Kind,
   ToolCallConfirmationDetails,
   ToolConfirmationOutcome,
+  ToolInvocation,
   ToolMcpConfirmationDetails,
-  Kind,
+  ToolResult,
 } from './tools.js';
-import { CallableTool, Part, FunctionCall } from '@google/genai';
+import { CallableTool, FunctionCall, Part } from '@google/genai';
 
 type ToolParams = Record<string, unknown>;
 
@@ -50,45 +52,25 @@ type McpContentBlock =
   | McpResourceBlock
   | McpResourceLinkBlock;
 
-export class DiscoveredMCPTool extends BaseTool<ToolParams, ToolResult> {
+class DiscoveredMCPToolInvocation extends BaseToolInvocation<
+  ToolParams,
+  ToolResult
+> {
   private static readonly allowlist: Set<string> = new Set();
 
   constructor(
     private readonly mcpTool: CallableTool,
     readonly serverName: string,
     readonly serverToolName: string,
-    description: string,
-    readonly parameterSchema: unknown,
+    readonly displayName: string,
     readonly timeout?: number,
     readonly trust?: boolean,
-    nameOverride?: string,
+    params: ToolParams = {},
   ) {
-    super(
-      nameOverride ?? generateValidName(serverToolName),
-      `${serverToolName} (${serverName} MCP Server)`,
-      description,
-      Kind.Other,
-      parameterSchema,
-      true, // isOutputMarkdown
-      false, // canUpdateOutput
-    );
-  }
-
-  asFullyQualifiedTool(): DiscoveredMCPTool {
-    return new DiscoveredMCPTool(
-      this.mcpTool,
-      this.serverName,
-      this.serverToolName,
-      this.description,
-      this.parameterSchema,
-      this.timeout,
-      this.trust,
-      `${this.serverName}__${this.serverToolName}`,
-    );
+    super(params);
   }
 
   async shouldConfirmExecute(
-    _params: ToolParams,
     _abortSignal: AbortSignal,
   ): Promise<ToolCallConfirmationDetails | false> {
     const serverAllowListKey = this.serverName;
@@ -99,8 +81,8 @@ export class DiscoveredMCPTool extends BaseTool<ToolParams, ToolResult> {
     }
 
     if (
-      DiscoveredMCPTool.allowlist.has(serverAllowListKey) ||
-      DiscoveredMCPTool.allowlist.has(toolAllowListKey)
+      DiscoveredMCPToolInvocation.allowlist.has(serverAllowListKey) ||
+      DiscoveredMCPToolInvocation.allowlist.has(toolAllowListKey)
     ) {
       return false; // server and/or tool already allowlisted
     }
@@ -110,23 +92,23 @@ export class DiscoveredMCPTool extends BaseTool<ToolParams, ToolResult> {
       title: 'Confirm MCP Tool Execution',
       serverName: this.serverName,
       toolName: this.serverToolName, // Display original tool name in confirmation
-      toolDisplayName: this.name, // Display global registry name exposed to model and user
+      toolDisplayName: this.displayName, // Display global registry name exposed to model and user
       onConfirm: async (outcome: ToolConfirmationOutcome) => {
         if (outcome === ToolConfirmationOutcome.ProceedAlwaysServer) {
-          DiscoveredMCPTool.allowlist.add(serverAllowListKey);
+          DiscoveredMCPToolInvocation.allowlist.add(serverAllowListKey);
         } else if (outcome === ToolConfirmationOutcome.ProceedAlwaysTool) {
-          DiscoveredMCPTool.allowlist.add(toolAllowListKey);
+          DiscoveredMCPToolInvocation.allowlist.add(toolAllowListKey);
         }
       },
     };
     return confirmationDetails;
   }
 
-  async execute(params: ToolParams): Promise<ToolResult> {
+  async execute(): Promise<ToolResult> {
     const functionCalls: FunctionCall[] = [
       {
         name: this.serverToolName,
-        args: params,
+        args: this.params,
       },
     ];
 
@@ -138,6 +120,63 @@ export class DiscoveredMCPTool extends BaseTool<ToolParams, ToolResult> {
       returnDisplay: getStringifiedResultForDisplay(rawResponseParts),
     };
   }
+
+  getDescription(): string {
+    return this.displayName;
+  }
+}
+
+export class DiscoveredMCPTool extends BaseDeclarativeTool<
+  ToolParams,
+  ToolResult
+> {
+  constructor(
+    private readonly mcpTool: CallableTool,
+    readonly serverName: string,
+    readonly serverToolName: string,
+    description: string,
+    readonly parameterSchema: unknown,
+    readonly timeout?: number,
+    readonly trust?: boolean,
+    nameOverride?: string,
+  ) {
+    super(
+      nameOverride ?? generateValidName(serverToolName),
+      `${serverToolName} (${serverName} MCP Server)`,
+      description,
+      Kind.Other,
+      parameterSchema,
+      true, // isOutputMarkdown
+      false, // canUpdateOutput
+    );
+  }
+
+  asFullyQualifiedTool(): DiscoveredMCPTool {
+    return new DiscoveredMCPTool(
+      this.mcpTool,
+      this.serverName,
+      this.serverToolName,
+      this.description,
+      this.parameterSchema,
+      this.timeout,
+      this.trust,
+      `${this.serverName}__${this.serverToolName}`,
+    );
+  }
+
+  protected createInvocation(
+    params: ToolParams,
+  ): ToolInvocation<ToolParams, ToolResult> {
+    return new DiscoveredMCPToolInvocation(
+      this.mcpTool,
+      this.serverName,
+      this.serverToolName,
+      this.displayName,
+      this.timeout,
+      this.trust,
+      params,
+    );
+  }
 }
 
 function transformTextBlock(block: McpTextBlock): Part {