feat(mcp): include request body in network tool output

Adds `includeBody` option to `browser_network_requests` MCP tool and
`--body` flag to the `network` CLI command to include POST/PUT/PATCH
request bodies in the network log output.

Author: yury-s

packages/playwright-core/src/tools/backend/network.ts

@@ -28,6 +28,7 @@ const requests = defineTabTool({
     description: 'Returns all network requests since loading the page',
     inputSchema: z.object({
       includeStatic: z.boolean().default(false).describe('Whether to include successful static resources like images, fonts, scripts, etc. Defaults to false.'),
+      includeBody: z.boolean().default(false).describe('Whether to include request body. Defaults to false.'),
       filename: z.string().optional().describe('Filename to save the network requests to. If not provided, requests are returned as text.'),
     }),
     type: 'readOnly',
@@ -39,7 +40,7 @@ const requests = defineTabTool({
     for (const request of requests) {
       if (!params.includeStatic && !isFetch(request) && isSuccessfulResponse(request))
         continue;
-      text.push(await renderRequest(request));
+      text.push(await renderRequest(request, params.includeBody));
     }
     await response.addResult('Network', text.join('\n'), { prefix: 'network', ext: 'log', suggestedFilename: params.filename });
   },
@@ -71,7 +72,7 @@ export function isFetch(request: playwright.Request): boolean {
   return ['fetch', 'xhr'].includes(request.resourceType());
 }
 
-export async function renderRequest(request: playwright.Request): Promise<string> {
+export async function renderRequest(request: playwright.Request, includeBody = false): Promise<string> {
   const response = request.existingResponse();
 
   const result: string[] = [];
@@ -80,6 +81,11 @@ export async function renderRequest(request: playwright.Request): Promise<string
     result.push(`=> [${response.status()}] ${response.statusText()}`);
   else if (request.failure())
     result.push(`=> [FAILED] ${request.failure()?.errorText ?? 'Unknown error'}`);
+  if (includeBody) {
+    const postData = request.postData();
+    if (postData)
+      result.push(`\n  Request body: ${postData}`);
+  }
   return result.join(' ');
 }
 

packages/playwright-core/src/tools/cli-daemon/commands.ts

@@ -743,10 +743,11 @@ const networkRequests = declareCommand({
   args: z.object({}),
   options: z.object({
     static: z.boolean().optional().describe('Whether to include successful static resources like images, fonts, scripts, etc. Defaults to false.'),
+    body: z.boolean().optional().describe('Whether to include request body. Defaults to false.'),
     clear: z.boolean().optional().describe('Whether to clear the network list'),
   }),
   toolName: ({ clear }) => clear ? 'browser_network_clear' : 'browser_network_requests',
-  toolParams: ({ static: includeStatic, clear }) => clear ? ({}) : ({ includeStatic }),
+  toolParams: ({ static: includeStatic, body: includeBody, clear }) => clear ? ({}) : ({ includeStatic, includeBody }),
 });
 
 const tracingStart = declareCommand({

tests/mcp/cli-devtools.spec.ts

@@ -64,6 +64,26 @@ test('network --static', async ({ cli, server }) => {
   expect(attachments[0].data.toString()).toContain(`[GET] ${`${server.PREFIX}/`} => [200] OK`);
 });
 
+test('network --body', async ({ cli, server }) => {
+  server.setContent('/', `
+    <button onclick="fetch('/api', { method: 'POST', headers: { 'Content-Type': 'application/json' }, body: JSON.stringify({ key: 'value' }) })">Click me</button>
+  `, 'text/html');
+  server.setContent('/api', '{}', 'application/json');
+  await cli('open', server.PREFIX);
+  await cli('click', 'e2');
+
+  {
+    const { attachments } = await cli('network');
+    expect(attachments[0].data.toString()).not.toContain('Request body:');
+  }
+
+  {
+    const { attachments } = await cli('network', '--body');
+    expect(attachments[0].data.toString()).toContain(`[POST] ${server.PREFIX}/api => [200] OK`);
+    expect(attachments[0].data.toString()).toContain('Request body: {"key":"value"}');
+  }
+});
+
 test('network --clear', async ({ cli, server }) => {
   await cli('open', server.PREFIX);
   await cli('eval', '() => fetch("/hello-world")');

tests/mcp/network.spec.ts

@@ -60,3 +60,43 @@ test('browser_network_requests', async ({ client, server }) => {
     expect(response.result).toContain(`[GET] ${`${server.PREFIX}/image.png`} => [404]`);
   }
 });
+
+test('browser_network_requests includes request payload', async ({ client, server }) => {
+  server.setContent('/', `
+    <button onclick="fetch('/api', { method: 'POST', headers: { 'Content-Type': 'application/json' }, body: JSON.stringify({ key: 'value' }) })">Click me</button>
+  `, 'text/html');
+
+  server.setContent('/api', '{}', 'application/json');
+
+  await client.callTool({
+    name: 'browser_navigate',
+    arguments: {
+      url: server.PREFIX,
+    },
+  });
+
+  await client.callTool({
+    name: 'browser_click',
+    arguments: {
+      element: 'Click me button',
+      ref: 'e2',
+    },
+  });
+
+  {
+    const response = parseResponse(await client.callTool({
+      name: 'browser_network_requests',
+    }));
+    expect(response.result).toContain(`[POST] ${server.PREFIX}/api => [200] OK`);
+    expect(response.result).not.toContain(`Request body:`);
+  }
+
+  {
+    const response = parseResponse(await client.callTool({
+      name: 'browser_network_requests',
+      arguments: { includeBody: true },
+    }));
+    expect(response.result).toContain(`[POST] ${server.PREFIX}/api => [200] OK`);
+    expect(response.result).toContain(`Request body: {"key":"value"}`);
+  }
+});