MCP Fetch

Instructions

Implementation Reference

• src/tools/puppeteer.ts:97-140 (handler)

  The main execution handler for the 'puppeteer' tool. It uses a switch statement on the action type to delegate to specific Puppeteer utility functions.
  export default async function puppeteer({ action }: InferSchema<typeof schema>) { try { switch (action.type) { // Browser actions case "list-browsers": return await listBrowsers() case "launch-browser": return await launchBrowser(action.headless, action.width, action.height, action.url) case "close-browser": return await closeBrowser(action.browserId) // Page actions case "list-pages": return await listPages() case "open-page": return await openPage(action.browserId, action.url) case "close-page": return await closePage(action.pageId) // Exec action case "exec-page": return await execPage(action.pageId, action.source) // Screenshot action case "take-screenshot": return await takeScreenshot(action.pageId, action.fullPage, action.format, action.quality) default: return JSON.stringify({ success: false, error: "Invalid action type", }, null, 2) } } catch (error) { return JSON.stringify({ success: false, error: error instanceof Error ? error.message : "Unknown error occurred", }, null, 2) } }
• src/tools/puppeteer.ts:13-82 (schema)

  Zod schema defining the input parameters for the puppeteer tool using a discriminated union based on 'action.type'.
  export const schema = { action: z.discriminatedUnion("type", [ // Browser actions z.object({ type: z.literal("list-browsers"), }), z.object({ type: z.literal("launch-browser"), headless: z.boolean() .optional() .default(false) .describe("Whether to run browser in headless mode. Defaults to false"), width: z.number() .optional() .default(1280) .describe("Browser window width in pixels. Defaults to 1280"), height: z.number() .optional() .default(720) .describe("Browser window height in pixels. Defaults to 720"), url: z.string() .optional() .describe("Optional URL to navigate to after launching the browser"), }), z.object({ type: z.literal("close-browser"), browserId: z.string().describe("The ID of the browser instance to close"), }), // Page actions z.object({ type: z.literal("list-pages"), }), z.object({ type: z.literal("open-page"), browserId: z.string().describe("The ID of the browser instance to create a page in"), url: z.string().optional().describe("Optional URL to navigate to after creating the page"), }), z.object({ type: z.literal("close-page"), pageId: z.string().describe("The ID of the page to close"), }), // Exec action z.object({ type: z.literal("exec-page"), pageId: z.string() .describe("The ID of the page to execute code on"), source: z.string() .describe("JavaScript code to execute. Will be executed outside of the page context. You can run commands like await page.goto('https://example.com') or await page.evaluate(() => { ... }). The code you write should return a string value that will serve as the result of the tool call."), }), // Screenshot action z.object({ type: z.literal("take-screenshot"), pageId: z.string() .describe("The ID of the page to take a screenshot of"), fullPage: z.boolean() .optional() .default(false) .describe("Whether to take a screenshot of the full scrollable page. Defaults to false"), format: z.enum(["png", "jpeg"]) .optional() .default("png") .describe("Image format for the screenshot. Defaults to png"), quality: z.number() .min(0) .max(100) .optional() .describe("Quality of the screenshot, only applicable for jpeg format (0-100)"), }), ]).describe("The action to perform with Puppeteer"), }
• src/tools/puppeteer.ts:85-94 (registration)

  Tool metadata that registers the tool with name 'puppeteer', description, and annotations for the MCP framework.
  export const metadata: ToolMetadata = { name: "puppeteer", description: "Control browsers and pages with Puppeteer - launch/close browsers, open/close pages, execute JavaScript, take screenshots, and more", annotations: { title: "Puppeteer Control", readOnlyHint: false, destructiveHint: false, idempotentHint: false, }, }