Advanced Hasura GraphQL MCP Server

Instructions

Implementation Reference

• src/index.ts:173-244 (handler)

  The core handler function that implements the logic for listing tables: introspects query_root fields, filters non-table fields, parses schema from descriptions, groups by schema, sorts, and returns JSON-formatted list.
  async ({ schemaName }) => { console.log(`[INFO] Executing tool 'list_tables' for schema: ${schemaName || 'ALL'}`); try { const schema = await getIntrospectionSchema(); const query = gql` query GetTablesWithDescriptions { __type(name: "query_root") { fields { name description type { name kind } } } } `; const result = await makeGqlRequest(query); const tablesData: Record<string, Array<{name: string, description: string | null}>> = {}; if (result.__type && result.__type.fields) { const fieldEntries = result.__type.fields; for (const field of fieldEntries) { if (field.name.includes('_aggregate') || field.name.includes('_by_pk') || field.name.includes('_stream') || field.name.includes('_mutation') || field.name.startsWith('__')) { continue; } let currentSchema = 'public'; if (field.description && field.description.includes('schema:')) { const schemaMatch = field.description.match(/schema:\s*([^\s,]+)/i); if (schemaMatch && schemaMatch[1]) { currentSchema = schemaMatch[1]; } } if (schemaName && currentSchema !== schemaName) { continue; } if (!tablesData[currentSchema]) { tablesData[currentSchema] = []; } tablesData[currentSchema].push({ name: field.name, description: field.description }); } } const formattedOutput = Object.entries(tablesData) .map(([schema, tables]) => ({ schema, tables: tables.sort((a, b) => a.name.localeCompare(b.name)) })) .sort((a, b) => a.schema.localeCompare(b.schema)); return { content: [{ type: "text", text: JSON.stringify(formattedOutput, null, 2) }] }; } catch (error: any) { console.error(`[ERROR] Tool 'list_tables' failed: ${error.message}`); throw error; } }
• src/index.ts:170-172 (schema)

  Zod input schema defining the optional 'schemaName' parameter for filtering tables by database schema.
  { schemaName: z.string().optional().describe("Optional. The database schema name to filter results. If omitted, returns tables from all schemas.") },
• src/index.ts:167-245 (registration)

  MCP server.tool call registering the 'list_tables' tool with name, description, input schema, and inline handler function.
  server.tool( "list_tables", "Lists available data tables (or collections) managed by Hasura, organized by schema with descriptions", { schemaName: z.string().optional().describe("Optional. The database schema name to filter results. If omitted, returns tables from all schemas.") }, async ({ schemaName }) => { console.log(`[INFO] Executing tool 'list_tables' for schema: ${schemaName || 'ALL'}`); try { const schema = await getIntrospectionSchema(); const query = gql` query GetTablesWithDescriptions { __type(name: "query_root") { fields { name description type { name kind } } } } `; const result = await makeGqlRequest(query); const tablesData: Record<string, Array<{name: string, description: string | null}>> = {}; if (result.__type && result.__type.fields) { const fieldEntries = result.__type.fields; for (const field of fieldEntries) { if (field.name.includes('_aggregate') || field.name.includes('_by_pk') || field.name.includes('_stream') || field.name.includes('_mutation') || field.name.startsWith('__')) { continue; } let currentSchema = 'public'; if (field.description && field.description.includes('schema:')) { const schemaMatch = field.description.match(/schema:\s*([^\s,]+)/i); if (schemaMatch && schemaMatch[1]) { currentSchema = schemaMatch[1]; } } if (schemaName && currentSchema !== schemaName) { continue; } if (!tablesData[currentSchema]) { tablesData[currentSchema] = []; } tablesData[currentSchema].push({ name: field.name, description: field.description }); } } const formattedOutput = Object.entries(tablesData) .map(([schema, tables]) => ({ schema, tables: tables.sort((a, b) => a.name.localeCompare(b.name)) })) .sort((a, b) => a.schema.localeCompare(b.schema)); return { content: [{ type: "text", text: JSON.stringify(formattedOutput, null, 2) }] }; } catch (error: any) { console.error(`[ERROR] Tool 'list_tables' failed: ${error.message}`); throw error; } } );