Class MCPToolWrapper

src/mcp/tool-wrapper.ts:14–116

 * to avoid collisions with builtins and across servers.
 */
export class MCPToolWrapper extends Tool<Record<string, unknown>> {
  readonly name: string;
  readonly description: string;
  readonly isReadOnly: boolean;
  readonly isDestructive: boolean;
  readonly argsSchema = z.record(z.any()) as unknown as z.ZodType<Record<string, unknown>>;

  constructor(
    private client: MCPClient,
    private toolDef: MCPToolDef,
    /** When the server is declared non-destructive, allow auto-approval. */
    serverDestructive: boolean = true,
  ) {
    super();
    this.name = `mcp:${client.name}:${toolDef.name}`;
    this.description = `[via MCP/${client.name}] ${toolDef.description ?? toolDef.name}`;
    // Conservative default: treat MCP tools as potentially mutating unless server says otherwise.
    this.isReadOnly = !serverDestructive;
    this.isDestructive = serverDestructive;
  }

  /** Override schema() to use the MCP-provided JSON Schema directly (skip zod conversion). */
  schema(): ToolSchema {
    const inputSchema = this.toolDef.inputSchema ?? { type: 'object', properties: {} };
    return {
      type: 'function',
      function: {
        name: this.name,
        description: this.description,
        parameters: inputSchema as ToolSchema['function']['parameters'],
      },
    };
  }

  async execute(args: Record<string, unknown>, ctx: ToolContext): Promise<ToolResult> {
    if (!this.client.isReady()) {
      return {
        content: `[MCP_UNAVAILABLE] MCP server '${this.client.name}' is not ready (state: ${this.client.status.state}, error: ${this.client.status.error ?? 'none'}). The agent cannot use this tool right now.`,
        isError: true,
      };
    }

    // Permission check (MCP tools go through the same engine as builtins)
    const permReq = {
      tool: this.name,
      operation: this.name,
      description: this.description,
    };
    const decision = ctx.permissions.evaluate(permReq);
    if (decision === 'deny') {
      return { content: `[PERMISSION_DENIED] Blocked by policy: ${this.name}`, isError: true };
    }
    if (decision === 'ask') {
      const summary = this.summarizeArgs(args);
      const answer = await ctx.askUser(
        `Run MCP tool ${this.name}${summary ? `\n  args: ${summary}` : ''}?`,
        ['yes', 'no', 'always'],
      );