prompts: document tool discovery in session-9p.md

- Global catalog: read /tools
- Loaded tools: read agent/tools
- Load a tool: write tool name to agent/tools
- Added tools to agent directory file table

data/prompts/session-9p.md

@@ -11,34 +11,38 @@ Access 9P files using the `ollie-9p` command (which auto-discovers the server vi
 | `agents`    | read   | Available agent names, one per line |
 | `backends`  | read   | Available backend names, one per line |
 | `models`    | read   | Available models (backend\tmodel per line) |
+| `tools`     | read   | Global tool catalog (all discoverable tools) |
 | `help`      | read   | Help text |
 | `ctl`       | write  | Server control commands (e.g. `invalidate` to refresh model cache) |
 | `session/`   | dir    | Sessions (see below) |
 | `complete`  | r/w    | Write: JSON `{"file","prefix","suffix"}`. Read: code completion result. |
 | `generate`  | r/w    | Write: JSON `{"prompt"}` or plain text. Read: one-shot LLM generation result. |
 | `route`     | r/w    | Write: task description. Read: `backend=X model=Y` recommendation. |
-| `tools`     | r/w    | Write: tool name. Read: tool's full prompt/documentation. |
 
-`complete`, `generate`, `route`, and `tools` are request-response files. Write a query, then read the response:
+`complete`, `generate`, and `route` are request-response files:
 
 ```bash
-# Get a tool's documentation
-echo 'file_edit' | ollie-9p rdwr tools
-# → returns file_edit's usage, args, and examples
-
-# Pick a backend+model for a task
 echo 'implement login page' | ollie-9p rdwr route
-# → returns "backend=anthropic model=claude-sonnet-4-20250514"
-
-# Generate text (one-shot, no session)
 echo '{"prompt":"summarize X"}' | ollie-9p rdwr generate
-# → returns the generated text
-
-# Get a code completion
 echo '{"file":"main.go","prefix":"func "}' | ollie-9p rdwr complete
-# → returns completion candidates
 ```
 
+## Tool Discovery
+
+Tools are loaded dynamically per-agent. The system has three levels:
+
+| Path | Purpose |
+|---|---|
+| `ollie-9p read tools` | **Global catalog** — all available tools on disk |
+| `ollie-9p read session/{id}/agent/{aid}/tools` | **Loaded tools** — tools active in this agent |
+| `echo "name" \| ollie-9p write session/{id}/agent/{aid}/tools` | **Load a tool** — activate it for this agent |
+
+- **List available tools** — `ollie-9p read tools` (global catalog with descriptions)
+- **See loaded tools** — `ollie-9p read session/{id}/agent/{aid}/tools`
+- **Load a tool** — `echo "toolname" | ollie-9p write session/{id}/agent/{aid}/tools` (or use `tool_load`)
+
+Once loaded, a tool becomes a first-class callable function with typed arguments. Load tools as needed — do not load everything upfront.
+
 ## Peer Agent Discovery
 
 Sessions sharing your `cwd` are your peer agents. Read `session/idx` to discover other sessions available for cooperation:
@@ -93,6 +97,7 @@ Each agent in a session gets its own subdirectory with its own plan, state, and
 
 | File | Mode | Purpose |
 |---|---|---|
+| `tools`       | r/w   | Read: loaded tools. Write: load a tool by name. |
 | `plan`        | r/w   | Markdown checklist; survives compaction; visible to peers |
 
 ## Operations