MySQL MCP Server

Instructions

Implementation Reference

• src/index.ts:417-466 (handler)

  The primary handler for the 'delete_data' tool. It validates the SQL query arguments, ensures it's a DELETE FROM query using isDeleteQuery helper, executes the query on the MySQL connection pool, logs the transaction, and returns a structured response with success/error details including the MySQL result.

  private async handleDeleteData(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 (!isDeleteQuery(query)) {
      throw new McpError(
        ErrorCode.InvalidParams,
        'Only DELETE FROM queries are allowed with delete_data tool.'
      );
    }
  
    console.error(`[${transactionId}] Executing DELETE query: ${query}`);
    
    try {
      const [result] = await this.pool.query(query);
      console.error(`[${transactionId}] Data deleted successfully`);
      
      return {
        content: [
          {
            type: 'text',
            text: JSON.stringify({
              success: true,
              message: 'Data deleted 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:150-163 (schema)

  The JSON schema definition for the 'delete_data' tool, including name, description, and input schema expecting a 'query' string parameter. This is returned in the ListTools response.

  {
    name: 'delete_data',
    description: 'Deletes data from a table in the MySQL database.',
    inputSchema: {
      type: 'object',
      properties: {
        query: {
          type: 'string',
          description: 'The SQL DELETE FROM query to execute.',
        },
      },
      required: ['query'],
    },
  },

• src/index.ts:195-196 (registration)

  Registration of the 'delete_data' tool handler within the CallToolRequestSchema request handler switch statement, dispatching tool calls to the handleDeleteData method.

  case 'delete_data':
    return this.handleDeleteData(request, transactionId);

• src/index.ts:46-48 (helper)

  Helper function used by the delete_data handler to validate that the provided SQL query starts with 'DELETE FROM' (case-insensitive).

  const isDeleteQuery = (query: string): boolean => 
    query.trim().toLowerCase().startsWith('delete from');