DocsFetcher MCP Server

Implementation Reference

• src/index.ts:187-224 (handler)

  The core async handler function for the 'fetch-package-docs' tool. Resolves package URL using getPackageUrl based on language, fetches and processes documentation using scraperService, returns content or error response.
  async ({ packageName, language = "javascript" }) => { console.error( `Fetching documentation for package: ${packageName} (${language})` ); try { const packageUrl = getPackageUrl(packageName, language); console.error(`Using package URL: ${packageUrl}`); const documentationContent = await scraperService.fetchLibraryDocumentation(packageUrl); return { content: [ { type: "text", text: documentationContent, }, ], }; } catch (error) { console.error("Error fetching package content:", error); const errorMessage = `Error fetching package documentation: ${ error instanceof Error ? error.message : String(error) }`; return { content: [ { type: "text", text: errorMessage, }, ], isError: true, }; } }
• src/index.ts:176-186 (schema)

  Zod input schema for the tool defining required packageName (string) and optional language (string).
  { packageName: z .string() .describe("Name of the package to fetch documentation for"), language: z .string() .optional() .describe( "Programming language or repository type (e.g., javascript, python, java, dotnet)" ), },
• src/index.ts:174-225 (registration)

  Registration of the 'fetch-package-docs' tool on the MCP server using server.tool(name, schema, handler).
  server.tool( "fetch-package-docs", { packageName: z .string() .describe("Name of the package to fetch documentation for"), language: z .string() .optional() .describe( "Programming language or repository type (e.g., javascript, python, java, dotnet)" ), }, async ({ packageName, language = "javascript" }) => { console.error( `Fetching documentation for package: ${packageName} (${language})` ); try { const packageUrl = getPackageUrl(packageName, language); console.error(`Using package URL: ${packageUrl}`); const documentationContent = await scraperService.fetchLibraryDocumentation(packageUrl); return { content: [ { type: "text", text: documentationContent, }, ], }; } catch (error) { console.error("Error fetching package content:", error); const errorMessage = `Error fetching package documentation: ${ error instanceof Error ? error.message : String(error) }`; return { content: [ { type: "text", text: errorMessage, }, ], isError: true, }; } } );
• src/utils/packageRepository.ts:32-102 (helper)

  Helper function that maps a package name and language to the corresponding package registry documentation URL (e.g., npm, PyPI, Maven, NuGet). Used by the handler to resolve the target URL.
  export function getPackageUrl( packageName: string, language = "javascript" ): string { const lang = language.toLowerCase().trim(); switch (lang) { // JavaScript/TypeScript case "javascript": case "js": case "typescript": case "ts": case "node": case "nodejs": case "npm": return `https://www.npmjs.com/package/${packageName}`; // Python case "python": case "py": case "pypi": return `https://pypi.org/project/${packageName}`; // Java case "java": case "maven": return `https://mvnrepository.com/artifact/${packageName}`; // .NET case "dotnet": case ".net": case "csharp": case "c#": case "nuget": return `https://www.nuget.org/packages/${packageName}`; // Ruby case "ruby": case "gem": case "rubygem": case "rubygems": return `https://rubygems.org/gems/${packageName}`; // PHP case "php": case "composer": case "packagist": return `https://packagist.org/packages/${packageName}`; // Rust case "rust": case "cargo": case "crate": case "crates": return `https://crates.io/crates/${packageName}`; // Go case "go": case "golang": return `https://pkg.go.dev/${packageName}`; // Swift case "swift": case "cocoapods": return `https://cocoapods.org/pods/${packageName}`; // Default to npm default: return `https://www.npmjs.com/package/${packageName}`; } }
• src/services/ScraperService.ts:137-195 (helper)

  Primary helper method called by the tool handler. Performs web scraping, crawling (up to maxPages), content extraction, and compilation into structured Markdown documentation, including summarization prompts.
  public async fetchLibraryDocumentation( url: string, maxPages = 5 ): Promise<string> { try { // If input is not a URL, assume it's a package name if (!url.startsWith("http")) { url = `https://www.npmjs.com/package/${url}`; } // Extract library name from URL const libraryName = extractLibraryName(url); // Crawl documentation const pages = await this.crawlDocumentation(url, libraryName, maxPages); if (pages.length === 0) { throw new Error(`Failed to fetch documentation from ${url}`); } // Compile documentation into a single markdown document const documentation = this.compileDocumentation(pages, libraryName); // Include instructions for using the prompt const promptInstructions = ` --- 🔍 For better summarization, use the "summarize-library-docs" prompt with: - libraryName: "${libraryName}" - documentation: <the content above> Example: @summarize-library-docs with libraryName="${libraryName}" `; return documentation + promptInstructions; } catch (error) { console.error(`Error fetching URL content:`, error); // Extract library name from URL const libraryName = extractLibraryName(url); const errorMessage = `Error fetching URL content: ${ error instanceof Error ? error.message : String(error) }`; // Include error-specific prompt instructions const promptInstructions = ` --- 🔍 For information about this library despite the fetch error, use the "summarize-library-docs" prompt with: - libraryName: "${libraryName}" - errorStatus: "${error instanceof Error ? error.message : String(error)}" Example: @summarize-library-docs with libraryName="${libraryName}" and errorStatus="fetch failed" `; return errorMessage + promptInstructions; } }