Playwright MCP Server

Instructions

Implementation Reference

• src/tools/browser/response.ts:21-37 (handler)

  Implements the core execution logic for the 'playwright_expect_response' tool using Playwright's page.waitForResponse to start waiting for a HTTP response matching the URL pattern, storing the promise for later assertion.
  export class ExpectResponseTool extends BrowserToolBase { /** * Execute the expect response tool */ async execute(args: ExpectResponseArgs, context: ToolContext): Promise<ToolResponse> { return this.safeExecute(context, async (page) => { if (!args.id || !args.url) { return createErrorResponse("Missing required parameters: id and url must be provided"); } const responsePromise = page.waitForResponse(args.url); responsePromises.set(args.id, responsePromise); return createSuccessResponse(`Started waiting for response with ID ${args.id}`); }); } }
• src/tools.ts:307-318 (schema)

  Defines the tool schema including name, description, input parameters (id and url), and validation requirements.
  { name: "playwright_expect_response", description: "Ask Playwright to start waiting for a HTTP response. This tool initiates the wait operation but does not wait for its completion.", inputSchema: { type: "object", properties: { id: { type: "string", description: "Unique & arbitrary identifier to be used for retrieving this response later with `Playwright_assert_response`." }, url: { type: "string", description: "URL pattern to match in the response." } }, required: ["id", "url"], }, },
• src/toolHandler.ts:508-509 (registration)

  Registers the tool handler in the main tool dispatching switch statement, delegating execution to the ExpectResponseTool instance.
  case "playwright_expect_response": return await expectResponseTool.execute(args, context);
• src/toolHandler.ts:329-329 (registration)

  Instantiates the ExpectResponseTool class instance used for handling tool calls.
  if (!expectResponseTool) expectResponseTool = new ExpectResponseTool(server);
• src/tools/codegen/generator.ts:125-130 (helper)

  Generates equivalent Playwright test code for the tool action during codegen session recording.
  private generateExpectResponseStep(parameters: Record<string, unknown>): string { const { url, id } = parameters; return ` // Wait for response const ${id}Response = page.waitForResponse('${url}');`; }