# MCP servers

Source: https://athas.dev/docs/mcp

Connect agent tools through MCP and understand transport, credentials, and permissions.

Model Context Protocol (MCP) servers expose tools to an agent, such as searching a service or
reading a database. Only configure a server whose executable or endpoint you trust.

## Add a server

Open **Settings > AI > MCP servers** and add a server. Choose the transport the server supports
and enter its command or endpoint. Configure required environment variables or headers without
putting secret values into project instructions.

Athas supports stdio, HTTP and SSE transports. A stdio server runs a local command; a remote
transport connects to the configured URL. Use the server's own setup instructions for arguments,
credentials and required runtimes.

## Select servers for agents

Enable the server to pass it to agents. An external agent may support only some transports;
Athas reports configured servers that were left out because that agent cannot use them.
A saved server definition alone does not prove the server connected or the agent can call its tools.

## Permissions and data

Read the tool name, arguments and scope before allowing a call. A tool can read or modify data
outside the editor, depending on the server's permissions. Project ignore files do not restrict
an MCP server's independent access.

## Connection problems

- For stdio, confirm the command works and its runtime is available.
- For remote servers, verify the URL, transport and required headers.
- Confirm credentials have the intended scope and have not expired.
- Check the selected agent supports the transport, then restart the affected session after changes.

See [Agent context](https://athas.dev/docs/agent-context) for instruction and ignore files, and
[Providers and Models](https://athas.dev/docs/ai-providers) for model connections.

## Install links

Server authors can offer an [Add to Athas link](https://athas.dev/docs/mcp-servers#add-to-athas-links) that pre-fills the server dialog. Review the command, endpoint and credentials before saving.