MySQL MCP Server

Instructions

Implementation Reference

• src/index.ts:311-361 (handler)

  The primary handler function for the 'insert_data' tool. It validates the input arguments, checks that the SQL query starts with 'INSERT INTO', executes the query using the MySQL connection pool, logs the transaction, and returns a success response with the query result or an error message.

  private async handleInsertData(request: any, transactionId: string) {
    if (!isValidSqlQueryArgs(request.params.arguments)) {
      throw new McpError(
        ErrorCode.InvalidParams,
        'Invalid SQL query arguments.'
      );
    }
  
    const query = request.params.arguments.query;
    
    if (!isInsertQuery(query)) {
      throw new McpError(
        ErrorCode.InvalidParams,
        'Only INSERT INTO queries are allowed with insert_data tool.'
      );
    }
  
    console.error(`[${transactionId}] Executing INSERT query: ${query}`);
    
    try {
      const [result] = await this.pool.query(query);
      console.error(`[${transactionId}] Data inserted successfully`);
      
      return {
        content: [
          {
            type: 'text',
            text: JSON.stringify({
              success: true,
              message: 'Data inserted successfully',
              result
            }, null, 2),
          },
        ],
      };
    } catch (error) {
      console.error(`[${transactionId}] Query error:`, error);
      if (error instanceof Error) {
        return {
          content: [
            {
              type: 'text',
              text: `MySQL error: ${error.message}`,
            },
          ],
          isError: true,
        };
      }
      throw error;
    }
  }

• src/index.ts:125-134 (schema)

  Input schema definition for the 'insert_data' tool, specifying an object with a required 'query' property of type string for the INSERT SQL statement.

  inputSchema: {
    type: 'object',
    properties: {
      query: {
        type: 'string',
        description: 'The SQL INSERT INTO query to execute.',
      },
    },
    required: ['query'],
  },

• src/index.ts:122-135 (registration)

  Registration of the 'insert_data' tool in the tools list returned by ListToolsRequestSchema handler, including name, description, and input schema.

  {
    name: 'insert_data',
    description: 'Inserts data into a table in the MySQL database.',
    inputSchema: {
      type: 'object',
      properties: {
        query: {
          type: 'string',
          description: 'The SQL INSERT INTO query to execute.',
        },
      },
      required: ['query'],
    },
  },

• src/index.ts:191-192 (registration)

  Dispatch registration in the CallToolRequestSchema switch statement that routes calls to 'insert_data' to the handleInsertData method.

  case 'insert_data':
    return this.handleInsertData(request, transactionId);

• src/index.ts:37-39 (helper)

  Helper function used by the handler to validate that the provided query is an INSERT INTO statement.

  // Check if query is for inserting data
  const isInsertQuery = (query: string): boolean => 
    query.trim().toLowerCase().startsWith('insert into');