MySQL MCP Server

Instructions

Implementation Reference

• src/index.ts:89-100 (handler)

  The handler function for the 'get-schema' tool. It extracts the schemaName from args, calls the getSchema helper, and returns the result as a JSON-formatted text content block.

  async (args) => {
    const schemaName = args.schemaName;
    const result = await getSchema(schemaName);
    return {
      content: [
        {
          type: "text",
          text: JSON.stringify(result, null, 2),
        }
      ]
    };
  }

• src/index.ts:83-83 (schema)

  Zod schema definition for the input parameter 'schemaName' of type string.

  schemaName: z.string().describe("The name of the schema"),

• src/index.ts:82-101 (registration)

  Registration of the 'get-schema' tool using server.tool, including name, description, input schema, metadata, and handler function.

  server.tool("get-schema", "Get the schema of a table", {
    schemaName: z.string().describe("The name of the schema"),
  }, {
    title: "Get Schema",
    readOnlyHint: true,
    destructiveHint: false,
  },
    async (args) => {
      const schemaName = args.schemaName;
      const result = await getSchema(schemaName);
      return {
        content: [
          {
            type: "text",
            text: JSON.stringify(result, null, 2),
          }
        ]
      };
    }
  );

• src/index.ts:58-80 (helper)

  Helper function that connects to the MySQL database using configuration, executes a DESCRIBE query on the specified schemaName (table), and returns the results or error.

  async function getSchema(schemaName: string) {
    // Create the connection to database using config (environment variables or command-line arguments)
    const connection = await mysql.createConnection({
      host: config.host,
      port: config.port,
      user: config.user,
      password: config.password,
      database: config.database,
    });
  
    try {
      const [results] = await connection.query(
        `DESCRIBE ${mysql.escapeId(schemaName)}`
      );
  
      return results;
    } catch (err) {
      console.log(err);
      return err;
    } finally {
      connection.end();
    }
  }