layered-soul/docs/MCP-INTEGRATION.md

# MCP Integration — Colibri as the Agent Coordination Hub

**LIVE VS PLANNED.** The building blocks are all real and in the repos today
(Hermes speaks MCP both directions; `colibri-mcp` exists; the board + poller/worker
loop and the cross-host bridge are live). What is **not yet wired** is the one setup
step this document describes: pointing each Hermes at `colibri-mcp` so the two
instances coordinate through the shared board. Sections are tagged `[LIVE]`,
`[SETUP]` (the work to do), or `[PLANNED]`.

---

## 1. What MCP is — and what "connect two Hermes" actually means

MCP (Model Context Protocol) is a **client → server tool-calling** protocol over
JSON-RPC. A client (an agent's LLM loop) connects to a server that advertises
**tools** and **resources**; the client calls them and gets results. It is **not** a
peer-to-peer chat bus and **not** a message queue.

So "connect two Hermes instances" has two distinct meanings:

- **(a) Tool sharing** — Hermes A invokes Hermes B's *own* tools (B's browser, B's
  files) by treating B as an MCP server. Point-to-point.
- **(b) Coordination** — the two instances hand work back and forth and share state.

Our fleet already does **(b)** through the Colibri board (register-agent → poll →
execute → done; see [`CAPABILITY-ROUTING.md`](./CAPABILITY-ROUTING.md)). The simplest,
highest-leverage MCP move is therefore to make MCP the **in-conversation interface to
that board**, not to wire the two Hermes mouth-to-mouth.

> **Expectation-set:** this gives each Hermes's LLM conversational read/write access to
> the shared board. It is **not** a live two-way chat between the instances. The
> **board is the shared state they meet at** — durable, inspectable, restart-safe.

---

## 2. [LIVE] What already exists

**Hermes is both an MCP server and an MCP client.**

- **Server** — `hermes mcp serve` (`mcp_serve.py`, FastMCP over stdio) exposes Hermes
  tools/conversations to any MCP client. Client config shape:
  ```json
  { "mcpServers": { "hermes": { "command": "hermes", "args": ["mcp", "serve"] } } }
  ```
- **Client** — Hermes consumes external MCP servers from its `mcp_servers` config
  (`hermes_cli/mcp_config.py`, managed via the `hermes mcp` subcommand; loaded by
  `tui_gateway/server.py`; refreshable in-session with `reload-mcp`). Each entry is
  the standard `command` / `args` / `env` (or `url`) shape; presets exist (e.g. Codex).

**Colibri ships a ready-made MCP server fronting the board: `colibri-mcp`.**

- Crate `crates/colibri-mcp` (binary `colibri-mcp`), a stdio JSON-RPC MCP server that
  wraps `colibri-client` and talks to the daemon over its Unix socket.
- Tool surface (`crates/colibri-mcp/src/lib.rs`):

  | Tool | Access | Description |
  |------|--------|-------------|
  | `colibri_status` | read | Daemon status (agents, sessions) |
  | `colibri_snapshot` | read | Glasspane snapshot (pane states) |
  | `colibri_list_tasks` | read | Tasks by status |
  | `colibri_list_skills` | read | Registered skills catalog |
  | `colibri_create_task` | write-gated | Create a task |
  | `colibri_intake_task` | write-gated | Submit intake task with `required_capabilities` |
  | `colibri_set_cost_mode` | write-gated | Switch cost mode (fast/smart/max) |

- Environment (`crates/colibri-mcp/src/main.rs`):
  - `COLIBRI_MCP_SOCKET` — daemon socket path (override)
  - `COLIBRI_DAEMON_SOCKET` — fallback socket path
  - `COLIBRI_MCP_WRITE=1` — enable the write-gated tools
  - `COLIBRI_MCP_EXTERNAL_CONFIG` / `COLIBRI_MCP_EXTERNAL_CALL=1` — proxy external MCP
    servers (see §6)
- Default daemon socket on FreeBSD: `/var/run/colibri/colibri.sock` (from the
  `colibri_daemon` rc.d). `colibri-mcp socket-path` prints the resolved path.

**Cross-host reach is already solved** — `colibri-mcp` connects to a daemon socket; a
*remote* daemon is reached via the `socat` bridge on `100.72.229.63:9190` (Tailscale-only;
see CAPABILITY-ROUTING `[LIVE] Cross-host topology`). osa-local instances just use the
local socket.

---

## 3. Architecture — hub-and-spoke, not mesh

```
   Hermes-osa-cli ──MCP──┐                  ┌──MCP── Hermes-osa-web
                         ▼                  ▼
                     colibri-mcp   (stdio JSON-RPC, one per Hermes)
                         │                  │
                         └────► colibri-daemon / board (SQLite) ◄────┘
                                  ▲  poller (2 min) / worker (5 min) loop
                                  │  executes tasks assigned by agent UUID
```

Each Hermes configures Colibri **once**. Adding a third agent is one more spoke — no
N×N wiring. The instances never connect to each other directly; they meet at the board.

**Flow:** Hermes A's LLM calls `colibri_create_task {required_capabilities:["freebsd"]}`
→ the daemon's scheduler assigns it to a matching agent's UUID → that agent's poll loop
(`scripts/colibri_poll.py`) picks up its own tasks, executes, and marks done
(`scripts/colibri_task_done.py`) → A reads the result with `colibri_list_tasks`.

This layers cleanly on the coordination model already built:

| Layer | Role | Source of truth |
|-------|------|-----------------|
| `colibri-mcp` tools | conversational read/write to the board (this doc) | — |
| poller / worker loop | autonomous execution of assigned tasks | scripts (PR #83) |
| board (SQLite) | shared state: agents, tasks, lifecycle | `colibri-store` |

---

## 4. [SETUP] Wiring it up (config, not code)

Per Hermes instance on osa:

1. **Provide the binary.** Build or stage `colibri-mcp`:
   ```sh
   cargo build --release -p colibri-mcp     # target/release/colibri-mcp
   ```
   Confirm it reaches the daemon: `colibri-mcp socket-path`.
2. **Register the server** in each Hermes's `mcp_servers` config (via `hermes mcp add`
   or the config file), giving the two instances distinct agent identities:
   ```yaml
   mcp_servers:
     colibri:
       command: /usr/local/bin/colibri-mcp
       env:
         COLIBRI_MCP_SOCKET: /var/run/colibri/colibri.sock
         COLIBRI_MCP_WRITE: "1"          # enable create/intake
   ```
3. **Reload tools** — `reload-mcp` in each Hermes; confirm the `colibri_*` tools appear.
4. **Validate end-to-end** — from cli-Hermes, create a `freebsd` task; confirm
   web-Hermes's loop runs it and the task flips to `done`.

> Keep the two instances on **separate `HERMES_HOME`** (shared `.env` is fine, shared
> state home is not — single-writer rule). Give them distinguishing capability tags if
> a task must land on a specific one (e.g. `web-ui` vs `cli`).

---

## 5. [LIVE] Security

- **Write tools are gated** by `COLIBRI_MCP_WRITE=1`. Leave it unset for read-only
  agents; set it only where an instance should create/assign work.
- **Socket, not network.** `colibri-mcp` talks to the daemon's Unix socket; the only
  network surface is the bridge, bound to the Tailscale IP with a `pf` rule — never
  `0.0.0.0`.
- **License:** `colibri-mcp` is AGPL-3.0-only; keep that in mind for any redistribution.

---

## 6. [PLANNED] Beyond coordination

- **External MCP proxying.** `colibri-mcp` can host *third-party* MCP servers
  (`COLIBRI_MCP_EXTERNAL_CONFIG` + `COLIBRI_MCP_EXTERNAL_CALL=1`), jail-wrapped on
  FreeBSD (`colibri-mcp` `external.rs` → `colibri_daemon::spawner::jail_wrap`). This lets
  the hub aggregate outside tools behind one MCP endpoint, confined per the
  capability/isolation model.
- **Tool-sharing mode (Option A).** If a real need arises for one Hermes to call
  another's *own* tools, expose the target with `hermes mcp serve` and add it as a spoke
  — but prefer the board for coordination; reserve direct tool-sharing for genuine
  capability borrowing, and accept the point-to-point cost.

---

## 7. Rejected alternative: direct Hermes ↔ Hermes mesh

Connecting A's client straight to B's `hermes mcp serve` was considered and **not
chosen** for coordination: it is a mesh (N×N config), stdio transport would have A
*spawn a new* B rather than reach the running one, and it bypasses the board that
already gives us durable, inspectable shared state. The hub (Option B above) reuses
everything and scales by adding spokes.

---

_See [`CAPABILITY-ROUTING.md`](./CAPABILITY-ROUTING.md) for the routing engine and
cross-host transport, and [`../AGENTS.md`](../AGENTS.md) for the agent matrix._