Skip to main content

MCP servers

Connect a Model Context Protocol server to give your agents access to the tools the server exposes. Unlike Custom API integrations, you don't define tools yourself — Stellar discovers them from the server and surfaces them to agents.

Connect a server​

Open Integrations, click + Add integration → API/MCP server, and pick MCP server.

You need to provide a name, the server URL, and optionally an auth connector if the server requires authentication. Unlike Custom API integrations, MCP servers have a single URL — they're not split per environment.

After saving, Stellar fetches the tool list from the server and caches it. You'll land on the integration detail page.

Tools tab​

The Tools tab on the MCP integration page shows the cached tool list as Stellar received it from the server. Each tool has its name, description, and parameter schema, all sourced from the server.

This list is read-only in Studio. Tools are authored on the MCP server side; Stellar doesn't let you edit them. If a tool's description or schema is wrong, fix it on the server.

Click Refresh now to re-fetch the tool list. Use this after the server's tools change — for example, after a new tool ships, or after you fix a description on the server side.

Make tools available to an agent​

From an agent's Actions tab, click + Add action and pick the MCP server as the source. The picker lists the server's cached tools; pick the one you want to add. The agent can then call that tool during conversations.

Each tool you add is added independently — you can pick three of the server's five tools and leave the other two out. The same per-agent overrides as shared API actions apply: conversation phases, max successful calls, and allowed states. The tool's name, description, and parameter schema all come from the server.

Runtime behavior​

When an agent has MCP tools linked, Stellar resolves them against the cached tool list at conversation start. If you've refreshed the cache recently, the agent picks up the new shape on the next conversation — there's no version-pinning, the same way shared actions work for Custom API.

If a tool you've linked is no longer present on the server when you refresh, the agent's Actions tab will flag it as a broken reference, and publishing the agent version will be blocked until you remove or re-link it.

Delete an integration​

Open the menu in the integration header and choose Delete. As with Custom API integrations, you can't delete an MCP server that has tools linked to active agents — remove those bindings first.

Next steps​