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diff --git a/packages/core/src/tools/tools.ts b/packages/core/src/tools/tools.ts
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+/**
+ * @license
+ * Copyright 2025 Google LLC
+ * SPDX-License-Identifier: Apache-2.0
+ */
+
+import { FunctionDeclaration, PartListUnion, Schema } from '@google/genai';
+
+/**
+ * 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;
+
+  /**
+   * Whether the tool's output should be rendered as markdown
+   */
+  isOutputMarkdown: boolean;
+
+  /**
+   * Whether the tool supports live (streaming) output
+   */
+  canUpdateOutput: boolean;
+
+  /**
+   * Validates the parameters for the tool
+   * Should be called from both `shouldConfirmExecute` and `execute`
+   * `shouldConfirmExecute` should return false immediately if invalid
+   * @param params Parameters to validate
+   * @returns An error message string if invalid, null otherwise
+   */
+  validateToolParams(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,
+    abortSignal: AbortSignal,
+  ): 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,
+    signal: AbortSignal,
+    updateOutput?: (output: string) => void,
+  ): 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 isOutputMarkdown Whether the tool's output should be rendered as markdown
+   * @param canUpdateOutput Whether the tool supports live (streaming) output
+   * @param parameterSchema JSON Schema defining the parameters
+   */
+  constructor(
+    readonly name: string,
+    readonly displayName: string,
+    readonly description: string,
+    readonly parameterSchema: Record<string, unknown>,
+    readonly isOutputMarkdown: boolean = true,
+    readonly canUpdateOutput: boolean = false,
+  ) {}
+
+  /**
+   * 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
+   * Should be called from both `shouldConfirmExecute` and `execute`
+   * `shouldConfirmExecute` should return false immediately if invalid
+   * @param params Parameters to validate
+   * @returns An error message string if invalid, null otherwise
+   */
+  // eslint-disable-next-line @typescript-eslint/no-unused-vars
+  validateToolParams(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(
+    // eslint-disable-next-line @typescript-eslint/no-unused-vars
+    params: TParams,
+    // eslint-disable-next-line @typescript-eslint/no-unused-vars
+    abortSignal: AbortSignal,
+  ): 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
+   * @param signal AbortSignal for tool cancellation
+   * @returns Result of the tool execution
+   */
+  abstract execute(
+    params: TParams,
+    signal: AbortSignal,
+    updateOutput?: (output: string) => void,
+  ): Promise<TResult>;
+}
+
+export interface ToolResult {
+  /**
+   * Content meant to be included in LLM history.
+   * This should represent the factual outcome of the tool execution.
+   */
+  llmContent: PartListUnion;
+
+  /**
+   * Markdown string for user display.
+   * This provides a user-friendly summary or visualization of the result.
+   * NOTE: This might also be considered UI-specific and could potentially be
+   * removed or modified in a further refactor if the server becomes purely API-driven.
+   * For now, we keep it as the core logic in ReadFileTool currently produces it.
+   */
+  returnDisplay: ToolResultDisplay;
+}
+
+export type ToolResultDisplay = string | FileDiff;
+
+export interface FileDiff {
+  fileDiff: string;
+  fileName: string;
+}
+
+export interface ToolEditConfirmationDetails {
+  type: 'edit';
+  title: string;
+  onConfirm: (outcome: ToolConfirmationOutcome) => Promise<void>;
+  fileName: string;
+  fileDiff: string;
+}
+
+export interface ToolExecuteConfirmationDetails {
+  type: 'exec';
+  title: string;
+  onConfirm: (outcome: ToolConfirmationOutcome) => Promise<void>;
+  command: string;
+  rootCommand: string;
+}
+
+export interface ToolMcpConfirmationDetails {
+  type: 'mcp';
+  title: string;
+  serverName: string;
+  toolName: string;
+  toolDisplayName: string;
+  onConfirm: (outcome: ToolConfirmationOutcome) => Promise<void> | void;
+}
+
+export type ToolCallConfirmationDetails =
+  | ToolEditConfirmationDetails
+  | ToolExecuteConfirmationDetails
+  | ToolMcpConfirmationDetails;
+
+export enum ToolConfirmationOutcome {
+  ProceedOnce = 'proceed_once',
+  ProceedAlways = 'proceed_always',
+  ProceedAlwaysServer = 'proceed_always_server',
+  ProceedAlwaysTool = 'proceed_always_tool',
+  Cancel = 'cancel',
+}