Remote MCP server with Postgres tools

Build a remote MCP server in this empty folder and deploy it to Volcano as a function, so coding agents and MCP clients like Insomnia can call its tools over HTTPS.

- Use the official MCP TypeScript SDK (@modelcontextprotocol/sdk) with the Streamable HTTP transport in stateless mode: no session ids, and a new server and transport for every request, because a function keeps nothing in memory between invocations. Answer GET and DELETE with 405.
- Three tools, backed by a bookmarks table in the project's Postgres: add_bookmark (url, title, optional note), search_bookmarks (optional text matched against title, URL and note, newest first, optional limit) and delete_bookmark (id).
- Every request must carry "Authorization: Bearer <token>". Generate a random token of at least 32 characters, store it as a Volcano variable named MCP_TOKEN, compare it in constant time, and answer 401 before parsing the body or touching the database.
- Validate tool inputs with zod before any query: http or https URLs only, URL up to 2048 characters, title 1 to 200, note up to 1000, query up to 100, limit up to 50, id a UUID. Refuse request bodies over 64 KB. Put the same length limits and a cap of 1000 rows in the database as well.
- Turn on row-level security on the table with no policies, so the project's anon key can't read or write it. The function reaches it with a service key that only the function's environment holds.
- Pin exact versions of every dependency.

Create a new Volcano project named bookmarks-mcp, deploy to production, and give me the MCP URL and the file that holds the token. Before you finish, test the live URL with the MCP SDK client: connect, list tools, add a bookmark, find it, delete it. Then show that a request without the token and an add_bookmark with an ftp:// URL are both refused.

# volcano/volcano-config.yaml
version: 1
functions:
  - name: mcp
    visibility: public
    invocation_mode: http
    http_auth_mode: none
    variable_scope: scoped
    variables: [MCP_TOKEN, VOLCANO_API_URL, VOLCANO_SERVICE_KEY, VOLCANO_DATABASE]

// volcano/functions/mcp/index.js
const supplied = auth.toLowerCase().startsWith('bearer ') ? auth.slice(7).trim() : '';
if (!supplied || !tokenMatches(supplied)) {   // sha256 both sides, crypto.timingSafeEqual
  return { statusCode: 401, headers: { 'www-authenticate': 'Bearer' }, body: '{"error":"missing or wrong bearer token"}' };
}
if (event.method !== 'POST') return { statusCode: 405, headers: { allow: 'POST' }, body: '' };

const server = buildServer();   // new McpServer + registerTool(...) with zod schemas
const transport = new WebStandardStreamableHTTPServerTransport({ sessionIdGenerator: undefined, enableJsonResponse: true });
await server.connect(transport);
const res = await transport.handleRequest(toRequest(event));
return { statusCode: res.status, headers: Object.fromEntries(res.headers), body: await res.text() };

const key = process.env.VOLCANO_SERVICE_KEY;
const volcano = new VolcanoAuth({ apiUrl: process.env.VOLCANO_API_URL, anonKey: key, accessToken: key });
volcano.database('app');

volcano init javascript && rm volcano/functions/hello.js
npm install --save-exact @modelcontextprotocol/sdk@1.32.2 @volcano.dev/sdk@2.2.0 zod@4.6.7
volcano projects create bookmarks-mcp
volcano use bookmarks-mcp
volcano cloud databases create app --region us-east-1 --pg-version 16
volcano projects keys service create mcp-function
# volcano/cloud.env holds the token and the service key; add it to .gitignore.
#   MCP_TOKEN=<openssl rand -hex 32>  VOLCANO_API_URL=https://api.volcano.dev
#   VOLCANO_SERVICE_KEY=<the key above>  VOLCANO_DATABASE=app
volcano cloud deploy --env-file volcano/cloud.env --with-migrations -d app
volcano cloud functions get mcp      # prints the Invoke URL

claude mcp add --transport http bookmarks https://<function-id>.functions.volcano.run/ \
  --header "Authorization: Bearer $MCP_TOKEN"