mcp4gql

import { z } from "zod"; import { executeGraphQL } from "../graphqlClient"; import { McpError, ErrorCode } from "@modelcontextprotocol/sdk/types.js"; import { getIntrospectionQuery } from "graphql"; // Import the helper // Define the Zod schema for the input (no parameters needed) export const IntrospectSchemaInput = z.object({}); // Define the expected output type (simplified, actual introspection result is complex) // We expect the result of executeGraphQL which includes data and errors interface IntrospectionResult { __schema: Record<string, any>; // Simplified representation } /** * Handler function for the introspectGraphQLSchema tool. * Fetches the GraphQL schema using introspection. * * @returns The GraphQL schema JSON. * @throws {McpError} If the introspection query fails. */ export async function handleIntrospection(): Promise<IntrospectionResult> { const introspectionQuery = getIntrospectionQuery(); // Get the standard query try { console.error("Executing GraphQL introspection query..."); const response = await executeGraphQL<IntrospectionResult>( introspectionQuery ); // Check for GraphQL errors returned in the response body if (response.errors && response.errors.length > 0) { const errorMessages = response.errors.map((e) => e.message).join("; "); console.error( `GraphQL introspection query returned errors: ${errorMessages}`, response.errors ); // Using InternalError as a placeholder. throw new McpError( ErrorCode.InternalError, `Introspection query failed: ${errorMessages}`, { details: response.errors } // Include original errors in details ); } if (!response.data || !response.data.__schema) { console.error( "Introspection query did not return a valid __schema object.", response.data ); // TODO: Revisit ErrorCode mapping once SDK types are clarified. // Using InternalError as a placeholder. throw new McpError( ErrorCode.InternalError, "Introspection query did not return a valid schema." ); } console.error("GraphQL introspection query successful."); return response.data; // Return the { data: { __schema: ... } } part } catch (error) { // Catch errors thrown by executeGraphQL (network, HTTP errors) or our own McpErrors console.error("Error executing introspection query:", error); if (error instanceof McpError) { // Re-throw McpErrors directly throw error; } // Wrap unexpected errors (using PascalCase) throw new McpError( ErrorCode.InternalError, "An unexpected error occurred during schema introspection.", { cause: error as Error } ); } }