gcp-spanner-list-databases
List all databases in a Google Cloud Spanner instance to manage and query database resources through the Google Cloud MCP Server.
Input Schema
TableJSON Schema
| Name | Required | Description | Default |
|---|---|---|---|
| instanceId | Yes | Spanner instance ID |
Implementation Reference
- src/services/spanner/tools.ts:349-429 (handler)The main execution handler for the 'gcp-spanner-list-databases' tool. Retrieves project ID from state or auth, creates Spanner client, lists databases for the given instanceId, formats results as Markdown table with project/instance info and resource URIs for tables/schema.
async ({ instanceId }, _extra) => { try { // First try to get the project ID from the state manager let projectId = stateManager.getCurrentProjectId(); if (!projectId) { // If not in state manager, try to get it from our function const authProjectId = await getProjectId(); if (authProjectId) { projectId = authProjectId; logger.debug(`Got project ID from getProjectId: ${projectId}`); } } else { logger.debug(`Got project ID from state manager: ${projectId}`); } if (!projectId) { throw new Error( "Project ID could not be determined. Please set a project ID using the set-project-id tool.", ); } // Create Spanner client with explicit project ID const spanner = new (await import("@google-cloud/spanner")).Spanner({ projectId: projectId, }); logger.debug( `Using Spanner client with project ID: ${projectId} for list-spanner-databases`, ); const instance = spanner.instance( Array.isArray(instanceId) ? instanceId[0] : instanceId, ); const [databases] = await instance.getDatabases(); if (!databases || databases.length === 0) { return { content: [ { type: "text", text: `# Spanner Databases\n\nProject: ${projectId}\nInstance: ${Array.isArray(instanceId) ? instanceId[0] : instanceId}\n\nNo databases found in the instance.`, }, ], }; } let markdown = `# Spanner Databases\n\nProject: ${projectId}\nInstance: ${Array.isArray(instanceId) ? instanceId[0] : instanceId}\n\n`; // Table header markdown += "| Database ID | State |\n"; markdown += "|-------------|-------|\n"; // Table rows for (const database of databases) { const metadata = database.metadata || {}; markdown += `| ${database.id || "unknown"} | ${metadata.state || "unknown"} |\n`; } // Add resource links for further exploration markdown += "\n## Available Resources\n\n"; for (const database of databases) { markdown += `- Tables in ${database.id}: \`gcp-spanner://${projectId}/${Array.isArray(instanceId) ? instanceId[0] : instanceId}/${database.id}/tables\`\n`; markdown += `- Schema for ${database.id}: \`gcp-spanner://${projectId}/${Array.isArray(instanceId) ? instanceId[0] : instanceId}/${database.id}/schema\`\n`; } return { content: [ { type: "text", text: markdown, }, ], }; } catch (error: any) { logger.error( `Error listing Spanner databases: ${error instanceof Error ? error.message : String(error)}`, ); throw error; } - Zod input schema for the tool, requiring 'instanceId' as a string.
{ instanceId: z.string().describe("Spanner instance ID"), }, - src/services/spanner/tools.ts:344-431 (registration)Direct registration of the tool via server.tool() call inside registerSpannerTools(), specifying name, schema, and inline handler.
server.tool( "gcp-spanner-list-databases", { instanceId: z.string().describe("Spanner instance ID"), }, async ({ instanceId }, _extra) => { try { // First try to get the project ID from the state manager let projectId = stateManager.getCurrentProjectId(); if (!projectId) { // If not in state manager, try to get it from our function const authProjectId = await getProjectId(); if (authProjectId) { projectId = authProjectId; logger.debug(`Got project ID from getProjectId: ${projectId}`); } } else { logger.debug(`Got project ID from state manager: ${projectId}`); } if (!projectId) { throw new Error( "Project ID could not be determined. Please set a project ID using the set-project-id tool.", ); } // Create Spanner client with explicit project ID const spanner = new (await import("@google-cloud/spanner")).Spanner({ projectId: projectId, }); logger.debug( `Using Spanner client with project ID: ${projectId} for list-spanner-databases`, ); const instance = spanner.instance( Array.isArray(instanceId) ? instanceId[0] : instanceId, ); const [databases] = await instance.getDatabases(); if (!databases || databases.length === 0) { return { content: [ { type: "text", text: `# Spanner Databases\n\nProject: ${projectId}\nInstance: ${Array.isArray(instanceId) ? instanceId[0] : instanceId}\n\nNo databases found in the instance.`, }, ], }; } let markdown = `# Spanner Databases\n\nProject: ${projectId}\nInstance: ${Array.isArray(instanceId) ? instanceId[0] : instanceId}\n\n`; // Table header markdown += "| Database ID | State |\n"; markdown += "|-------------|-------|\n"; // Table rows for (const database of databases) { const metadata = database.metadata || {}; markdown += `| ${database.id || "unknown"} | ${metadata.state || "unknown"} |\n`; } // Add resource links for further exploration markdown += "\n## Available Resources\n\n"; for (const database of databases) { markdown += `- Tables in ${database.id}: \`gcp-spanner://${projectId}/${Array.isArray(instanceId) ? instanceId[0] : instanceId}/${database.id}/tables\`\n`; markdown += `- Schema for ${database.id}: \`gcp-spanner://${projectId}/${Array.isArray(instanceId) ? instanceId[0] : instanceId}/${database.id}/schema\`\n`; } return { content: [ { type: "text", text: markdown, }, ], }; } catch (error: any) { logger.error( `Error listing Spanner databases: ${error instanceof Error ? error.message : String(error)}`, ); throw error; } }, ); - src/index.ts:170-170 (registration)Top-level call to registerSpannerTools(server) in the main server initialization, which triggers the tool registrations including gcp-spanner-list-databases.
registerSpannerTools(server);