MCP PostgreSQL Server

Instructions

Implementation Reference

• src/index.ts:418-445 (handler)

  The handler function for list_tables tool. Ensures database connection, queries information_schema.tables for tables in the given schema (default 'public'), returns table names as JSON, handles errors.

  private async handleListTables(args: any = {}) {
    await this.ensureConnection();
  
    const schema = args.schema || 'public';
  
    try {
      const result = await this.client!.query(`
        SELECT table_name
        FROM information_schema.tables
        WHERE table_schema = $1
        ORDER BY table_name
      `, [schema]);
      
      return {
        content: [
          {
            type: 'text',
            text: JSON.stringify(result.rows, null, 2),
          },
        ],
      };
    } catch (error) {
      throw new McpError(
        ErrorCode.InternalError,
        `Failed to list tables: ${getErrorMessage(error)}`
      );
    }
  }

• src/index.ts:223-232 (schema)

  Input schema for list_tables tool, defining an optional 'schema' string parameter.

  inputSchema: {
    type: 'object',
    properties: {
      schema: {
        type: 'string',
        description: 'Schema name (default: public)',
      },
    },
    required: [],
  },

• src/index.ts:220-233 (registration)

  Registration of the list_tables tool in the ListToolsRequestSchema response, including name, description, and input schema.

  {
    name: 'list_tables',
    description: 'List tables in the database',
    inputSchema: {
      type: 'object',
      properties: {
        schema: {
          type: 'string',
          description: 'Schema name (default: public)',
        },
      },
      required: [],
    },
  },

• src/index.ts:265-266 (registration)

  Routing logic in the CallToolRequestSchema handler that dispatches list_tables calls to the handleListTables method.

  case 'list_tables':
    return await this.handleListTables(request.params.arguments);