playwright_expect_response

Initiate waiting for HTTP responses in browser automation tests to verify network interactions and validate expected API calls or page loads.

Instructions

Ask Playwright to start waiting for a HTTP response. This tool initiates the wait operation but does not wait for its completion.

Input Schema

TableJSON Schema

Name	Required	Description	Default
`id`	Yes	Unique & arbitrary identifier to be used for retrieving this response later with `Playwright_assert_response`.
`url`	Yes	URL pattern to match in the response.

Implementation Reference

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

The ExpectResponseTool class implements the core logic for the 'playwright_expect_response' tool. It sets up a Playwright page.waitForResponse promise for the given URL and stores it in a map keyed by the provided ID for later retrieval.

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:337-353 (schema)

Tool metadata including name, description, and input schema (JSON Schema) for 'playwright_expect_response'.

{
  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:400-401 (registration)

Instantiation of the ExpectResponseTool instance in the initializeTools function.

if (!expectResponseTool) expectResponseTool = new ExpectResponseTool(server);
if (!assertResponseTool) assertResponseTool = new AssertResponseTool(server);

src/toolHandler.ts:609-610 (registration)
Switch case in handleToolCall that dispatches execution to expectResponseTool.execute
```
case "playwright_expect_response":
  return await expectResponseTool.execute(args, context);
```
src/tools/browser/response.ts:6-7 (helper)
Global map storing pending response promises by ID, used by both expect and assert tools.
```
const responsePromises = new Map<string, Promise<Response>>();
```

mcp-playwright