Playwright MCP Server

Instructions

Implementation Reference

• src/tools/codegen/index.ts:42-81 (handler)

  The core handler function implementing the start_codegen_session tool. It merges user-provided options with defaults, normalizes the output path, creates the output directory if needed, starts an ActionRecorder session, associates the options with the session, and returns session details.

  handler: async ({ options = {} }: { options?: CodegenOptions }) => {
    try {
      // Merge provided options with defaults
      const mergedOptions = { ...DEFAULT_OPTIONS, ...options };
  
      // Ensure output path is absolute and normalized
      const workspaceRoot = getWorkspaceRoot();
      const outputPath = path.isAbsolute(mergedOptions.outputPath)
        ? mergedOptions.outputPath
        : path.join(workspaceRoot, mergedOptions.outputPath);
  
      mergedOptions.outputPath = outputPath;
  
      // Ensure output directory exists
      try {
        await fs.mkdir(outputPath, { recursive: true });
      } catch (mkdirError: any) {
        throw new Error(
          `Failed to create output directory: ${mkdirError.message}`
        );
      }
  
      const sessionId = ActionRecorder.getInstance().startSession();
  
      // Store options with the session
      const recorder = ActionRecorder.getInstance();
      const session = recorder.getSession(sessionId);
      if (session) {
        session.options = mergedOptions;
      }
  
      return {
        sessionId,
        options: mergedOptions,
        message: `Started codegen session. Tests will be generated in: ${outputPath}`,
      };
    } catch (error: any) {
      throw new Error(`Failed to start codegen session: ${error.message}`);
    }
  },

• src/tools/codegen/index.ts:28-41 (schema)

  Input parameter schema definition for the start_codegen_session tool, specifying the optional 'options' object with properties for outputPath, testNamePrefix, and includeComments.

  parameters: {
    type: "object",
    properties: {
      options: {
        type: "object",
        description: "Code generation options",
        properties: {
          outputPath: { type: "string" },
          testNamePrefix: { type: "string" },
          includeComments: { type: "boolean" },
        },
      },
    },
  },

• src/tools.ts:7-35 (registration)

  Tool registration definition in createToolDefinitions(), including name, description, and detailed inputSchema with requirements for MCP protocol.

  {
    name: "start_codegen_session",
    description: "Start a new code generation session to record Playwright actions",
    inputSchema: {
      type: "object",
      properties: {
        options: {
          type: "object",
          description: "Code generation options",
          properties: {
            outputPath: { 
              type: "string", 
              description: "Directory path where generated tests will be saved (use absolute path)" 
            },
            testNamePrefix: { 
              type: "string", 
              description: "Prefix to use for generated test names (default: 'GeneratedTest')" 
            },
            includeComments: { 
              type: "boolean", 
              description: "Whether to include descriptive comments in generated tests" 
            }
          },
          required: ["outputPath"]
        }
      },
      required: ["options"]
    }
  },

• src/toolHandler.ts:332-333 (handler)

  Dispatch handler in the main tool call switch statement that invokes the specific startCodegenSession.handler with arguments.

  case "start_codegen_session":
    return await handleCodegenResult(startCodegenSession.handler(args));

• src/tools.ts:437-442 (registration)

  Listing of the tool name in CODEGEN_TOOLS array for categorization and conditional handling.

  export const CODEGEN_TOOLS = [
    'start_codegen_session',
    'end_codegen_session',
    'get_codegen_session',
    'clear_codegen_session'
  ];