MySQL MCP Server

Instructions

Implementation Reference

• src/index.ts:486-536 (handler)

  Primary handler for 'execute_sql' tool: validates input, forbids SELECT queries, executes SQL on MySQL pool, returns JSON result or error.

  private async handleExecuteSql(request: any, transactionId: string) {
    if (!isValidSqlQueryArgs(request.params.arguments)) {
      throw new McpError(
        ErrorCode.InvalidParams,
        'SQL 查询参数无效。'
      );
    }
  
    const query = request.params.arguments.query;
  
    if (isReadOnlyQuery(query)) {
      throw new McpError(
        ErrorCode.InvalidParams,
        'execute_sql 工具不允许 SELECT 查询。'
      );
    }
  
    console.error(`[${transactionId}] 执行通用 SQL: ${query}`);
  
    try {
      const [result] = await this.pool.query(query);
      console.error(`[${transactionId}] SQL 执行成功`);
  
      return {
        content: [
          {
            type: 'text',
            text: JSON.stringify({
              success: true,
              message: 'SQL 执行成功',
              result
            }, null, 2),
          },
        ],
      };
    } catch (error) {
      console.error(`[${transactionId}] SQL 执行出错:`, error);
      if (error instanceof Error) {
        return {
          content: [
            {
              type: 'text',
              text: `MySQL 错误: ${error.message}`,
            },
          ],
          isError: true,
        };
      }
      throw error;
    }
  }

• src/index.ts:172-185 (registration)

  Tool registration in ListToolsResponse: defines name, description, and inputSchema for execute_sql.

  {
    name: 'execute_sql',
    description: '执行任意非 SELECT 的 SQL 语句（如 ALTER TABLE、DROP 等）',
    inputSchema: {
      type: 'object',
      properties: {
        query: {
          type: 'string',
          description: '要执行的 SQL 语句',
        },
      },
      required: ['query'],
    },
  },

• src/index.ts:206-207 (registration)

  Dispatch/registration in CallToolRequest handler switch statement.

  case 'execute_sql':
    return this.handleExecuteSql(request, transactionId);

• src/index.ts:175-184 (schema)

  Input schema: requires 'query' string for SQL statement.

  inputSchema: {
    type: 'object',
    properties: {
      query: {
        type: 'string',
        description: '要执行的 SQL 语句',
      },
    },
    required: ['query'],
  },

• src/index.ts:26-30 (helper)

  Helper function to validate SQL query arguments used in execute_sql handler.

  const isValidSqlQueryArgs = (args: any): args is SqlQueryArgs =>
    typeof args === 'object' &&
    args !== null &&
    typeof args.query === 'string';