Stand up an MCP server from scratch

A Model Context Protocol (MCP) server is a process that exposes a list of tools over a small JSON-RPC protocol. Tale registers an MCP server once at the org level; from then on, every agent whose tools tab includes that server can call its tools. This walk takes a brand-new MCP server from "empty repo" to "called by an agent in a chat" on one Tale instance.

You need a Developer role, a host that can run the MCP server (your laptop is fine for the walk; a managed service or container for production), and an HTTPS URL Tale can reach. Cloud orgs reach public URLs by default; self-hosted instances need network access to wherever the MCP server runs.

Before you begin

Confirm two things. You have Node 20 or Python 3.11 installed — the official MCP SDKs target those runtimes. The Tale instance can reach your MCP server's URL — for local development, an ngrok tunnel or equivalent works; for production, host the server somewhere with a stable HTTPS endpoint. The conceptual side of MCP in Tale lives in Agent tools; this walk is the wiring.

Step 1 — Scaffold the server

The first move is generating the minimum MCP server — one tool, one handler. The official SDK does the protocol plumbing so you only write the tool.

npm create mcp-server@latest hello-tale
cd hello-tale

Open src/index.ts and replace the example tool with one that returns the current time in a named timezone:

server.tool(
  'current_time',
  'Return the current time in a given timezone',
  { timezone: z.string() },
  async ({ timezone }) => {
    const now = new Date().toLocaleString('en-US', { timeZone: timezone });
    return { content: [{ type: 'text', text: now }] };
  },
);

Run the server locally:

npm run start

The server listens on http://localhost:3000/mcp by default. The scaffold is in place; nothing in Tale knows about it yet.

Step 2 — Expose it on HTTPS

MCP servers Tale can call need an HTTPS URL with a valid certificate. For local development, point an ngrok tunnel at port 3000 and copy the public URL the tunnel prints. For production, host the server behind your normal ingress — Caddy, Nginx, a managed function, anything that terminates TLS.

Verify the public URL responds to a health check:

curl -sS "https://abcd.ngrok.app/mcp/health"

A 200 confirms reachability. A 502 or timeout means the tunnel is not forwarding; restart it or check the firewall.

Step 3 — Register the server in Tale

A reachable MCP server is invisible to Tale until you register it. Open Settings > Integrations > MCP servers and click New server. Fill in:

• Name — Hello Tale time
• URL — the public HTTPS URL from Step 2 (e.g. https://abcd.ngrok.app/mcp)
• Auth — bearer token if your server requires it, none for the walk

Click Save. Tale calls the server's list_tools method to discover the tool inventory; the panel shows current_time with its description. The server is now registered org-wide.

Step 4 — Attach the server to an agent and call the tool

A registered server is reachable only by agents that opt in. Open any agent, click Tools > MCP, toggle Hello Tale time on, and save. Open a chat with the agent and ask "what time is it in Tokyo right now". The chat renders a current_time tool-call card; expanding it shows { "timezone": "Asia/Tokyo" } and the timestamp your server returned, and the agent's reply uses the timestamp.

Where this fits

An MCP server is the right shape when a tool needs to live outside Tale — code your team owns, a service in another network, a third-party API you wrap. Custom tools in Build a custom tool are the right shape when the tool is one-off and lives inside one org's settings.

For the bigger picture of how tools widen what an agent can do, see Agent tools. For wiring an integration that wraps a third-party API instead of your own code, Integrations overview is the next read.