mcp4gql

#!/usr/bin/env node import { Server } from "@modelcontextprotocol/sdk/server/index.js"; import { StdioServerTransport } from "@modelcontextprotocol/sdk/server/stdio.js"; import { CallToolRequestSchema, ListToolsRequestSchema, McpError, ErrorCode, TextContent, } from "@modelcontextprotocol/sdk/types.js"; import zodToJsonSchema from "zod-to-json-schema"; import { z } from "zod"; // Import tool handlers and schemas import { handleIntrospection, IntrospectSchemaInput, } from "./tools/introspection"; import { handleExecution, ExecutorSchemaInput } from "./tools/executor"; import config from "./config"; // Load configuration (ensures validation runs early) // MCP Server setup const server = new Server( { name: "helm-graphql-mcp-server", version: "0.1.0", // TODO: Update version from package.json? }, { capabilities: { tools: {}, // Indicate tool capability }, } ); // ListTools Handler server.setRequestHandler(ListToolsRequestSchema, async () => { console.error("Handling ListTools request"); try { // Convert Zod schemas to JSON Schemas const introspectionInputSchema = zodToJsonSchema(IntrospectSchemaInput); const executeInputSchema = zodToJsonSchema(ExecutorSchemaInput); return { tools: [ { name: "introspectGraphQLSchema", description: "Fetches the schema of the target GraphQL API using introspection. Returns the schema in JSON format.", inputSchema: introspectionInputSchema, }, { name: "executeGraphQLOperation", description: "Executes an arbitrary GraphQL query or mutation against the target API. Use introspectGraphQLSchema first to understand the available operations.", inputSchema: executeInputSchema, }, ], }; } catch (error) { console.error("Error generating tool schemas:", error); // If schema generation fails, it's an internal server error // TODO: Revisit ErrorCode mapping once SDK types are clarified. throw new McpError( ErrorCode.InternalError, "Failed to generate tool schemas" ); } }); // CallTool Handler server.setRequestHandler(CallToolRequestSchema, async (request) => { const { name, arguments: args } = request.params; console.error(`Handling CallTool request for tool: ${name}`); try { let result: any; switch (name) { case "introspectGraphQLSchema": // Validate arguments using the Zod schema IntrospectSchemaInput.parse(args); console.error(`Calling handler for ${name}`); result = await handleIntrospection(); break; case "executeGraphQLOperation": // Validate arguments using the Zod schema const validatedArgs = ExecutorSchemaInput.parse(args); console.error(`Calling handler for ${name}`); result = await handleExecution(validatedArgs); break; default: console.warn(`Received request for unknown tool: ${name}`); // TODO: Revisit ErrorCode mapping once SDK types are clarified. throw new McpError(ErrorCode.InternalError, `Unknown tool: ${name}`); // Placeholder } console.error(`Tool ${name} executed successfully`); // Format result as JSON string within TextContent const responseContent: TextContent = { type: "text", text: JSON.stringify(result, null, 2), // Pretty print JSON }; return { content: [responseContent], }; } catch (error) { console.error(`Error executing tool ${name}:`, error); if (error instanceof McpError) { // Re-throw known MCP errors throw error; } else if (error instanceof z.ZodError) { // Handle Zod validation errors console.error("Input validation failed:", error.errors); // TODO: Revisit ErrorCode mapping once SDK types are clarified. throw new McpError( ErrorCode.InternalError, // Placeholder for InvalidInput `Invalid input for tool ${name}: ${error.errors .map((e) => `${e.path.join(".")} - ${e.message}`) .join("; ")}`, { details: error.format() } ); } else { // Wrap unexpected errors // TODO: Revisit ErrorCode mapping once SDK types are clarified. throw new McpError( ErrorCode.InternalError, `An unexpected error occurred while executing tool ${name}.`, { cause: error as Error } ); } } }); // Main function to start the server async function main() { console.error(`Starting Helm MCP Server (Phase 1)...`); console.error(`Connecting to GraphQL Endpoint: ${config.graphqlEndpoint}`); if (!config.authToken) { console.warn( "Auth token is not set. Requests may fail if API requires authentication." ); } const transport = new StdioServerTransport(); try { await server.connect(transport); console.error("Helm MCP Server connected and running via stdio."); } catch (error) { console.error("Failed to connect or start server:", error); process.exit(1); } } // Run the server main().catch((error) => { console.error("Fatal error during server execution:", error); process.exit(1); });