MySQL Query MCP Server

Instructions

Implementation Reference

• src/tools/environments.ts:20-72 (handler)

  The main handler function that executes the 'environments' tool logic: filters and lists available MySQL environments based on configured environment variables.
  export async function runEnvironmentsTool(_params?: z.infer<typeof EnvironmentsToolSchema>): Promise<{ content: { type: string; text: string }[] }> { try { debug('=== Running environments tool ==='); // Log all environment variables for debugging const envVars = Object.keys(process.env) .filter(key => key.includes('_DB_')) .reduce((acc, key) => ({ ...acc, [key]: process.env[key] }), {}); debug('Found DB-related environment variables:', envVars); const environments = Object.values(Environment.enum).filter(env => { const envPrefix = ENV_PREFIX_MAP[env]; // Check only for required variables that pools.ts uses const hasConfig = !!( process.env[`${envPrefix}_DB_HOST`] && process.env[`${envPrefix}_DB_USER`] && process.env[`${envPrefix}_DB_NAME`] ); debug(`Checking ${env} (${envPrefix}):`, { prefix: envPrefix, host: process.env[`${envPrefix}_DB_HOST`], user: process.env[`${envPrefix}_DB_USER`], db: process.env[`${envPrefix}_DB_NAME`], hasConfig }); return hasConfig; }); debug('Available environments:', environments); // Return the environments in the format expected by the MCP protocol return { content: [{ type: "text", text: JSON.stringify({ environments, count: environments.length, debug: { envVars, environments } }, null, 2), }], }; } catch (error) { debug('Error in environments tool:', error); throw error; } }
• src/tools/environments.ts:4-6 (schema)

  Tool name, description, and Zod input schema definition (empty object since no parameters required).
  export const environmentsToolName = "environments"; export const environmentsToolDescription = "List available MySQL database environments"; export const EnvironmentsToolSchema = z.object({});
• src/index.ts:138-145 (registration)

  Registration of the 'environments' tool in the MCP server capabilities, including description and input schema.
  [environmentsToolName]: { description: environmentsToolDescription, inputSchema: { type: "object", properties: {}, required: [], }, },
• src/index.ts:236-242 (registration)

  Dispatch handler in CallToolRequestSchema that validates arguments and calls the runEnvironmentsTool function.
  case environmentsToolName: { debug('Validating environments tool arguments...'); const validated = EnvironmentsToolSchema.parse(args); debug('Validated environments tool args:', validated); debug('Executing environments tool...'); return await runEnvironmentsTool(validated); }
• src/types/index.ts:66-66 (schema)

  Type definition for the 'environments' tool in the MySQLTools interface.
  environments: Tool;