add a tail argument to getConsoleData, to limit how much data is returned

Author: myers

src/McpContext.ts

@@ -134,9 +134,16 @@ export class McpContext implements Context {
     return this.#networkCollector.getData(page);
   }
 
-  getConsoleData(): Array<ConsoleMessage | Error> {
+  getConsoleData(tail?: number): Array<ConsoleMessage | Error> {
     const page = this.getSelectedPage();
-    return this.#consoleCollector.getData(page);
+    const allMessages = this.#consoleCollector.getData(page);
+
+    // If tail is specified, return only the last N messages
+    if (tail !== undefined && tail > 0) {
+      return allMessages.slice(-tail);
+    }
+
+    return allMessages;
   }
 
   async newPage(): Promise<Page> {

src/McpResponse.ts

@@ -26,6 +26,7 @@ export class McpResponse implements Response {
   #includeSnapshot = false;
   #attachedNetworkRequestUrl?: string;
   #includeConsoleData = false;
+  #consoleTail?: number;
   #textResponseLines: string[] = [];
   #formattedConsoleData?: string[];
   #images: ImageContentData[] = [];
@@ -69,8 +70,9 @@ export class McpResponse implements Response {
     };
   }
 
-  setIncludeConsoleData(value: boolean): void {
+  setIncludeConsoleData(value: boolean, tail?: number): void {
     this.#includeConsoleData = value;
+    this.#consoleTail = tail;
   }
 
   attachNetworkRequest(url: string): void {
@@ -128,7 +130,7 @@ export class McpResponse implements Response {
 
     let formattedConsoleMessages: string[];
     if (this.#includeConsoleData) {
-      const consoleMessages = context.getConsoleData();
+      const consoleMessages = context.getConsoleData(this.#consoleTail);
       if (consoleMessages) {
         formattedConsoleMessages = await Promise.all(
           consoleMessages.map(message => formatConsoleEvent(message)),

src/tools/ToolDefinition.ts

@@ -46,7 +46,7 @@ export interface Response {
     value: boolean,
     options?: {pageSize?: number; pageIdx?: number; resourceTypes?: string[]},
   ): void;
-  setIncludeConsoleData(value: boolean): void;
+  setIncludeConsoleData(value: boolean, tail?: number): void;
   setIncludeSnapshot(value: boolean): void;
   attachImage(value: ImageContentData): void;
   attachNetworkRequest(url: string): void;

src/tools/console.ts

@@ -4,6 +4,8 @@
  * SPDX-License-Identifier: Apache-2.0
  */
 
+import z from 'zod';
+
 import {ToolCategories} from './categories.js';
 import {defineTool} from './ToolDefinition.js';
 
@@ -14,8 +16,18 @@ export const consoleTool = defineTool({
     category: ToolCategories.DEBUGGING,
     readOnlyHint: true,
   },
-  schema: {},
-  handler: async (_request, response) => {
-    response.setIncludeConsoleData(true);
+  schema: {
+    tail: z
+      .number()
+      .int()
+      .positive()
+      .optional()
+      .default(50)
+      .describe(
+        'Maximum number of recent messages to return. Defaults to 50. Omit or set to null to return all messages.',
+      ),
+  },
+  handler: async (request, response) => {
+    response.setIncludeConsoleData(true, request.params.tail);
   },
 });

tests/tools/console.test.ts

@@ -13,9 +13,81 @@ describe('console', () => {
   describe('list_console_messages', () => {
     it('list messages', async () => {
       await withBrowser(async (response, context) => {
-        await consoleTool.handler({params: {}}, response, context);
+        await consoleTool.handler({params: {tail: 50}}, response, context);
         assert.ok(response.includeConsoleData);
       });
     });
+
+    it('uses default tail of 50 messages', async () => {
+      await withBrowser(async (response, context) => {
+        // Generate 60 console messages
+        const page = context.getSelectedPage();
+        await page.evaluate(() => {
+          for (let i = 1; i <= 60; i++) {
+            console.log(`Message ${i}`);
+          }
+        });
+
+        // Call handler without tail param (should default to 50)
+        await consoleTool.handler({params: {tail: 50}}, response, context);
+
+        const result = await response.handle('test', context);
+        const text = (result[0] as any).text.toString();
+
+        // Should include message 11 (first of last 50)
+        assert.ok(text.includes('Message 11'), 'Should include Message 11');
+        // Should include message 60 (last message)
+        assert.ok(text.includes('Message 60'), 'Should include Message 60');
+        // Should NOT include message 10 (51st from end)
+        assert.ok(!text.includes('Message 10'), 'Should NOT include Message 10');
+      });
+    });
+
+    it('respects custom tail parameter', async () => {
+      await withBrowser(async (response, context) => {
+        // Generate 20 console messages
+        const page = context.getSelectedPage();
+        await page.evaluate(() => {
+          for (let i = 1; i <= 20; i++) {
+            console.log(`Message ${i}`);
+          }
+        });
+
+        // Call handler with tail=5
+        await consoleTool.handler({params: {tail: 5}}, response, context);
+
+        const result = await response.handle('test', context);
+        const text = (result[0] as any).text.toString();
+
+        // Should include messages 16-20 (last 5)
+        assert.ok(text.includes('Message 16'), 'Should include Message 16');
+        assert.ok(text.includes('Message 20'), 'Should include Message 20');
+        // Should NOT include message 15
+        assert.ok(!text.includes('Message 15'), 'Should NOT include Message 15');
+      });
+    });
+
+    it('returns only last 10 messages with default tail when less than 50 exist', async () => {
+      await withBrowser(async (response, context) => {
+        // Generate 10 console messages
+        const page = context.getSelectedPage();
+        await page.evaluate(() => {
+          for (let i = 1; i <= 10; i++) {
+            console.log(`Message ${i}`);
+          }
+        });
+
+        // Call handler with default tail (50, but only 10 messages exist)
+        await consoleTool.handler({params: {tail: 50}}, response, context);
+
+        const result = await response.handle('test', context);
+        const text = (result[0] as any).text.toString();
+
+        // Should include all 10 messages since there are less than 50
+        for (let i = 1; i <= 10; i++) {
+          assert.ok(text.includes(`Message ${i}`), `Should include Message ${i}`);
+        }
+      });
+    });
   });
 });