# `Issho.MCP.Session`
[🔗](https://github.com/hattoriai/issho/blob/v0.4.0/lib/issho/mcp.ex#L31)

Who an MCP caller is in Issho's rooms: the `Issho.Tool.Context` its
tool calls run with. The one place where an MCP endpoint's
authorization (Sake's, your own, or none) meets Issho: the agent and
the options of its joins come from the call.

The settings, in the app's config or from `Issho.MCP.Setup`:

    config :issho, Issho.MCP,
      instance: MyApp.Issho,
      agent: {MyApp.Collaboration, :agent},
      idle: 600_000

`agent` is `{module, function}` or a function of one argument, called
with the call's `Sake.Context` (its `scope` is the principal your
endpoint's authorization put there; nil without one). It gives
`{actor, opts}`: the agent, and the options of its joins
(`:on_behalf_of`, `:claims`, `:can`):

    def agent(%Sake.Context{scope: %MyApp.User{} = user}),
      do: {%{id: "assistant:#{user.id}", name: "Assistant", kind: :agent}, on_behalf_of: user}

    def agent(%Sake.Context{scope: %MyApp.Service{} = service}),
      do: {%{id: "service:#{service.id}", name: service.name, kind: :service}, []}

Without `agent`, the caller is an agent named for its MCP client
("Claude Code"): on behalf of the principal when the principal is an
`Issho.Actor`, or acting as itself when there is none.

# `context`

```elixir
@spec context(Sake.Context.t()) :: Issho.Tool.Context.t()
```

The context a call's tools run with.

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*Consult [api-reference.md](api-reference.md) for complete listing*