list-spanner-tables
Lists all tables in a Google Cloud Spanner database to help users understand database structure and manage data organization.
Input Schema
TableJSON Schema
| Name | Required | Description | Default |
|---|---|---|---|
| instanceId | No | Spanner instance ID (defaults to SPANNER_INSTANCE env var) | |
| databaseId | No | Spanner database ID (defaults to SPANNER_DATABASE env var) |
Implementation Reference
- src/services/spanner/tools.ts:136-205 (handler)Handler function that executes the list-spanner-tables tool. It connects to the Spanner database using provided or default instanceId and databaseId, queries the information_schema.tables to list all tables along with their column counts, formats the results as a Markdown table, and includes resource links for further exploration.async ({ instanceId, databaseId }, _extra) => { try { const projectId = await getProjectId(); const config = await getSpannerConfig( Array.isArray(instanceId) ? instanceId[0] : instanceId, Array.isArray(databaseId) ? databaseId[0] : databaseId ); const spanner = await getSpannerClient(); console.log(`Using Spanner client with project ID: ${spanner.projectId} for execute-spanner-query`); const instance = spanner.instance(config.instanceId); const database = instance.database(config.databaseId); // Query for tables // Execute query to list tables const [tablesResult] = await database.run({ sql: `SELECT t.table_name, (SELECT COUNT(1) FROM information_schema.columns WHERE table_name = t.table_name) as column_count FROM information_schema.tables t WHERE t.table_catalog = '' AND t.table_schema = '' ORDER BY t.table_name` }); if (!tablesResult || tablesResult.length === 0) { return { content: [{ type: 'text', text: `# Spanner Tables\n\nProject: ${projectId}\nInstance: ${config.instanceId}\nDatabase: ${config.databaseId}\n\nNo tables found in the database.` }] }; } let markdown = `# Spanner Tables\n\nProject: ${projectId}\nInstance: ${config.instanceId}\nDatabase: ${config.databaseId}\n\n`; // Table header markdown += '| Table Name | Column Count |\n'; markdown += '|------------|-------------|\n'; // Table rows for (const row of tablesResult) { // Access the row properties directly // Extract table name and column count const tableName = (row as any).table_name as string || 'unknown'; const columnCount = (row as any).column_count as number || 0; markdown += `| ${tableName} | ${columnCount} |\n`; } // Add resource links for further exploration markdown += '\n## Available Resources\n\n'; markdown += `- Schema: \`gcp-spanner://${projectId}/${config.instanceId}/${config.databaseId}/schema\`\n`; for (const row of tablesResult) { const tableName = (row as any).table_name as string || 'unknown'; markdown += `- Table Preview: \`gcp-spanner://${projectId}/${config.instanceId}/${config.databaseId}/tables/${tableName}/preview\`\n`; } return { content: [{ type: 'text', text: markdown }] }; } catch (error: any) { console.error('Error listing Spanner tables:', error); throw error; } }
- Input schema for the list-spanner-tables tool using Zod validation, with optional instanceId and databaseId parameters.{ instanceId: z.string().optional().describe('Spanner instance ID (defaults to SPANNER_INSTANCE env var)'), databaseId: z.string().optional().describe('Spanner database ID (defaults to SPANNER_DATABASE env var)') },
- src/services/spanner/tools.ts:130-206 (registration)Registration of the list-spanner-tables tool on the MCP server within the registerSpannerTools function.server.tool( 'list-spanner-tables', { instanceId: z.string().optional().describe('Spanner instance ID (defaults to SPANNER_INSTANCE env var)'), databaseId: z.string().optional().describe('Spanner database ID (defaults to SPANNER_DATABASE env var)') }, async ({ instanceId, databaseId }, _extra) => { try { const projectId = await getProjectId(); const config = await getSpannerConfig( Array.isArray(instanceId) ? instanceId[0] : instanceId, Array.isArray(databaseId) ? databaseId[0] : databaseId ); const spanner = await getSpannerClient(); console.log(`Using Spanner client with project ID: ${spanner.projectId} for execute-spanner-query`); const instance = spanner.instance(config.instanceId); const database = instance.database(config.databaseId); // Query for tables // Execute query to list tables const [tablesResult] = await database.run({ sql: `SELECT t.table_name, (SELECT COUNT(1) FROM information_schema.columns WHERE table_name = t.table_name) as column_count FROM information_schema.tables t WHERE t.table_catalog = '' AND t.table_schema = '' ORDER BY t.table_name` }); if (!tablesResult || tablesResult.length === 0) { return { content: [{ type: 'text', text: `# Spanner Tables\n\nProject: ${projectId}\nInstance: ${config.instanceId}\nDatabase: ${config.databaseId}\n\nNo tables found in the database.` }] }; } let markdown = `# Spanner Tables\n\nProject: ${projectId}\nInstance: ${config.instanceId}\nDatabase: ${config.databaseId}\n\n`; // Table header markdown += '| Table Name | Column Count |\n'; markdown += '|------------|-------------|\n'; // Table rows for (const row of tablesResult) { // Access the row properties directly // Extract table name and column count const tableName = (row as any).table_name as string || 'unknown'; const columnCount = (row as any).column_count as number || 0; markdown += `| ${tableName} | ${columnCount} |\n`; } // Add resource links for further exploration markdown += '\n## Available Resources\n\n'; markdown += `- Schema: \`gcp-spanner://${projectId}/${config.instanceId}/${config.databaseId}/schema\`\n`; for (const row of tablesResult) { const tableName = (row as any).table_name as string || 'unknown'; markdown += `- Table Preview: \`gcp-spanner://${projectId}/${config.instanceId}/${config.databaseId}/tables/${tableName}/preview\`\n`; } return { content: [{ type: 'text', text: markdown }] }; } catch (error: any) { console.error('Error listing Spanner tables:', error); throw error; } } );
- src/index.ts:140-140 (registration)Top-level registration call for all Spanner tools, including list-spanner-tables, in the main server setup.registerSpannerTools(server);