> ## Documentation Index
> Fetch the complete documentation index at: https://docs.rebuno.io/llms.txt
> Use this file to discover all available pages before exploring further.

# MCP servers

> Give Uber's sessions tools from MCP servers

`config/mcp.json` lists the MCP servers a session can turn on, in pi's format.
Servers authenticate with headers. In a header, `${GITHUB_TOKEN}` is the
session's [GitHub token](/uber/getting-started#github-access), the one it uses
for git, limited to its repository and renewed on every dispatch, so GitHub's
MCP server needs no token of its own:

```json theme={"theme":{"light":"min-light","dark":"material-theme-ocean"}}
{
  "mcpServers": {
    "github": {
      "url": "https://api.githubcopilot.com/mcp/",
      "headers": {
        "Authorization": "Bearer ${GITHUB_TOKEN}",
        "X-MCP-Tools": "issue_read,list_issues,search_issues,..."
      }
    }
  }
}
```

A turn's `mcp` lists the servers to turn on, from `mcp.json` or registered by an
extension with `pi.registerMcpServer()`. The session keeps the list until a
turn sends another, and subagents use it:

```bash theme={"theme":{"light":"min-light","dark":"material-theme-ocean"}}
rebuno exec create uber '{"task": "Triage the open issues.", "mcp": ["github"]}' --session triage
```

Each server's tools are named `mcp__<server>__<tool>` and run as recorded steps
under [policy](/policy). A server's tool list is recorded too, so a replay
builds the same prompt without connecting.


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