1 files changed, 147 insertions, 0 deletions
diff --git a/packages/cli/src/tools/tools.ts b/packages/cli/src/tools/tools.ts
new file mode 100644
index 00000000..21dd88d5
--- /dev/null
+++ b/packages/cli/src/tools/tools.ts
@@ -0,0 +1,147 @@
+import { FunctionDeclaration, Schema } from "@google/genai";
+import { ToolCallConfirmationDetails } from "../ui/types.js";
+
+/**
+ * Interface representing the base Tool functionality
+ */
+export interface Tool<TParams = unknown, TResult extends ToolResult = ToolResult> {
+  /**
+   * The internal name of the tool (used for API calls)
+   */
+  name: string;
+
+  /**
+   * The user-friendly display name of the tool
+   */
+  displayName: string;
+
+  /**
+   * Description of what the tool does
+   */
+  description: string;
+
+  /**
+   * Function declaration schema from @google/genai
+   */
+  schema: FunctionDeclaration;
+
+  /**
+   * Validates the parameters for the tool
+   * @param params Parameters to validate
+   * @returns An error message string if invalid, null otherwise
+   */
+  invalidParams(params: TParams): string | null;
+
+  /**
+   * Gets a pre-execution description of the tool operation
+   * @param params Parameters for the tool execution
+   * @returns A markdown string describing what the tool will do
+   * Optional for backward compatibility
+   */
+  getDescription(params: TParams): string;
+
+  /**
+   * Determines if the tool should prompt for confirmation before execution
+   * @param params Parameters for the tool execution
+   * @returns Whether execute should be confirmed.
+   */
+  shouldConfirmExecute(params: TParams): Promise<ToolCallConfirmationDetails | false>;
+
+  /**
+   * Executes the tool with the given parameters
+   * @param params Parameters for the tool execution
+   * @returns Result of the tool execution
+   */
+  execute(params: TParams): Promise<TResult>;
+}
+
+
+/**
+ * Base implementation for tools with common functionality
+ */
+export abstract class BaseTool<TParams = unknown, TResult extends ToolResult = ToolResult> implements Tool<TParams, TResult> {
+  /**
+   * Creates a new instance of BaseTool
+   * @param name Internal name of the tool (used for API calls)
+   * @param displayName User-friendly display name of the tool
+   * @param description Description of what the tool does
+   * @param parameterSchema JSON Schema defining the parameters
+   */
+  constructor(
+    public readonly name: string,
+    public readonly displayName: string,
+    public readonly description: string,
+    public readonly parameterSchema: Record<string, unknown>
+  ) {}
+
+  /**
+   * Function declaration schema computed from name, description, and parameterSchema
+   */
+  get schema(): FunctionDeclaration {
+    return {
+      name: this.name,
+      description: this.description,
+      parameters: this.parameterSchema as Schema
+    };
+  }
+
+  /**
+   * Validates the parameters for the tool
+   * This is a placeholder implementation and should be overridden
+   * @param params Parameters to validate
+   * @returns An error message string if invalid, null otherwise
+   */
+  invalidParams(params: TParams): string | null {
+    // Implementation would typically use a JSON Schema validator
+    // This is a placeholder that should be implemented by derived classes
+    return null;
+  }
+
+  /**
+   * Gets a pre-execution description of the tool operation
+   * Default implementation that should be overridden by derived classes
+   * @param params Parameters for the tool execution
+   * @returns A markdown string describing what the tool will do
+   */
+  getDescription(params: TParams): string {
+    return JSON.stringify(params);
+  }
+
+  /**
+   * Determines if the tool should prompt for confirmation before execution
+   * @param params Parameters for the tool execution
+   * @returns Whether or not execute should be confirmed by the user.
+   */
+  shouldConfirmExecute(params: TParams): Promise<ToolCallConfirmationDetails | false> {
+    return Promise.resolve(false);
+  }
+
+  /**
+   * Abstract method to execute the tool with the given parameters
+   * Must be implemented by derived classes
+   * @param params Parameters for the tool execution
+   * @returns Result of the tool execution
+   */
+  abstract execute(params: TParams): Promise<TResult>;
+}
+
+
+export interface ToolResult {
+  /**
+   * Content meant to be included in LLM history.
+   * This should represent the factual outcome of the tool execution.
+   */
+  llmContent: string;
+
+  /**
+   * Markdown string for user display.
+   * This provides a user-friendly summary or visualization of the result.
+   */
+  returnDisplay: ToolResultDisplay;
+}
+
+export type ToolResultDisplay = string | FileDiff;
+
+export interface FileDiff {
+  fileDiff: string
+}