DocsFetcher MCP Server

Implementation Reference

• src/index.ts:187-225 (handler)

  The handler function for the 'fetch-package-docs' tool. It resolves the package URL using getPackageUrl based on language, fetches the documentation using scraperService, and returns the content or error.
  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)

  Input schema for the 'fetch-package-docs' tool using Zod validation for packageName (required string) and optional language.
  { 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, specifying name, input schema, and handler function.
  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 getPackageUrl used by the tool handler to map package names and languages to appropriate documentation repository URLs.
  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)

  Key helper method fetchLibraryDocumentation in ScraperService, called by the tool to scrape and compile documentation from the resolved package URL.
  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; } }