---
title: "MCP servers"
description: "Connect a remote MCP server and every tool it exposes becomes available to your agents mid-conversation, without defining each tool by hand."
---

If you already run a tool server that speaks the
[Model Context Protocol](https://modelcontextprotocol.io), you can plug it
into ThunderPhone directly. Add the server once under
**Connections → MCP** (`/dashboard/mcp-connections`); its tools are
discovered automatically and can be attached to any agent.

ThunderPhone connects to MCP servers over **Streamable HTTP** — that is
the only supported transport, so the server must be reachable at an HTTP
URL (stdio-only local servers won't work).

## Add a server

<Steps>
  <Step title="Click Add server">
    Give the server a **name** and its **URL** (for example
    `https://example.com/mcp`).
  </Step>
  <Step title="Add headers if the server needs them">
    Add any static HTTP headers the server requires — typically an
    `Authorization` header. Header values are write-only and encrypted at
    rest: when you edit the server later, leave a value blank to keep the
    existing one.
  </Step>
  <Step title="Save and sync">
    Saving immediately synchronizes the server's tool list. The server
    card shows every discovered tool by name; if none appear, the server
    responded but advertised no tools.
  </Step>
</Steps>

## Manage servers

Each server card shows its URL and cached tool list, with controls to:

- **Enable/disable** the server without deleting it.
- **Sync tools** — re-fetch the tool list after the server changes.
- **Edit** the name, URL, or headers.
- **Delete** the server.

<Note>
  Tool lists are cached from the last sync. If you add or change tools on
  your server, click **Sync tools** so agents see the new set.
</Note>

## Attach it to an agent

A connected server does nothing until an agent uses it. Open the agent in
the builder ([Build an agent](/guides/build-an-agent)) and attach the
server in its MCP section — the server's tools then become callable
during that agent's conversations.

## Next steps

<CardGroup cols={2}>
  <Card title="Use ThunderPhone as an MCP server" icon="server" href="/guides/thunderphone-mcp-server">
    Let an external AI client list agents, place calls, and inspect call results.
  </Card>
  <Card title="API connections" icon="plug" href="/guides/api-connections">
    A single HTTP endpoint as an agent function — no MCP server needed.
  </Card>
  <Card title="Connect apps" icon="cable" href="/guides/connect-apps">
    Prebuilt Google, Slack, HubSpot, Salesforce, and Cal.com tools.
  </Card>
</CardGroup>