1# weather — example zut extension (Go, tool-providing)
2
3Demonstrates the **tool registration** half of the extension protocol
4(phase 2). The extension exposes a `weather(city)` tool that the LLM
5can invoke; the result is fake-but-deterministic so repeated calls
6for the same city return the same thing.
7
8## Build
9
10```bash
11cd examples/extensions/weather
12go build -o weather .
13```
14
15## Install
16
17```bash
18zut ext install .
19```
20
21Copies the directory (manifest + binary) into
22`$ZUT_HOME/extensions/weather/`. zut picks it up the next time you
23launch the TUI and registers the tool with the agent.
24
25## Use
26
27In zut, ask:
28
29- "What's the weather in Berlin?"
30- "Compare the weather in Tokyo and Reykjavik."
31
32The model decides on its own to call the `weather` tool because the
33description tells it what the tool is for. You don't need to invoke
34anything by hand.
35
36## Add the leading slash to your /help table
37
38The tool also shows up in the system prompt's tool list because zut
39folds extension tools into the agent's registry at startup.
40
41## See also
42
43- `examples/extensions/hello` — slash-command extension (Go SDK)
44- `examples/extensions/clock` — slash-command extension (Node, no SDK)
45- `docs/extensions.md` — full protocol reference