run_sql_query
Execute read-only SQL SELECT queries to retrieve data from a MySQL database. This tool enables data analysis and information extraction through direct database queries.
Instructions
Executes a read-only SQL query (SELECT statements only) against the MySQL database.
Input Schema
TableJSON Schema
| Name | Required | Description | Default |
|---|---|---|---|
| query | Yes | The SQL SELECT query to execute. |
Implementation Reference
- src/index.ts:208-255 (handler)Core handler for 'run_sql_query' tool: validates arguments and query type (SELECT only), executes query on MySQL connection pool, returns JSON-stringified rows or error response.
// Handle read-only queries (SELECT) private async handleReadQuery(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 (!isReadOnlyQuery(query)) { throw new McpError( ErrorCode.InvalidParams, 'Only SELECT queries are allowed with run_sql_query tool.' ); } console.error(`[${transactionId}] Executing SELECT query: ${query}`); try { const [rows] = await this.pool.query(query); console.error(`[${transactionId}] Query executed successfully`); return { content: [ { type: 'text', text: JSON.stringify(rows, 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:97-106 (schema)Input schema definition for the 'run_sql_query' tool, specifying a required 'query' string parameter.
inputSchema: { type: 'object', properties: { query: { type: 'string', description: 'The SQL SELECT query to execute.', }, }, required: ['query'], }, - src/index.ts:94-107 (registration)Tool registration in ListToolsRequestSchema response: defines name, description, and input schema for 'run_sql_query'.
{ name: 'run_sql_query', description: 'Executes a read-only SQL query (SELECT statements only) against the MySQL database.', inputSchema: { type: 'object', properties: { query: { type: 'string', description: 'The SQL SELECT query to execute.', }, }, required: ['query'], }, }, - src/index.ts:187-188 (registration)Dispatch logic in CallToolRequestSchema handler: routes 'run_sql_query' calls to the handleReadQuery method.
case 'run_sql_query': return this.handleReadQuery(request, transactionId); - src/index.ts:29-31 (helper)Helper function used by handler to validate that the query is a read-only SELECT statement.
// Check if query is read-only (SELECT) const isReadOnlyQuery = (query: string): boolean => query.trim().toLowerCase().startsWith('select');