# Agents and thinking

An agent variant sets three things: how much the model deliberates, which tools it is
offered, and a behaviour appendix in the system prompt.

```bash
shiro --agent deep              # at launch
shiro --agent plan --think low  # variant with an overridden level
```

```
/agent          picker
/agent review   direct
/think          picker
/think max      direct
```

## The variants

| Variant | Thinking | Tools | Steps | For |
|---|---|---|---|---|
| `default` | medium | all | 50 | ordinary work |
| `quick` | off | all | 12 | small, well-scoped edits |
| `deep` | max | all | 80 | hard problems, unclear causes |
| `plan` | high | read-only | 50 | investigate and propose |
| `review` | high | read-only | 50 | critique a change |

**`quick`** tells the model not to deliberate, not to write a task list, and not to explore
beyond what the change needs. Good for a rename or a one-line fix where thinking budget is
pure latency.

**`deep`** asks for more than one hypothesis before acting, more reading before concluding,
and findings recorded with `remember` so they survive compaction.

**`plan`** and **`review`** are genuinely read-only. `write_file`, `edit_file`, `multi_edit`,
and `bash` are withheld from the model, not merely discouraged in prose — a model that cannot
see a tool cannot call it. They keep everything that only reads, including `read_many_files`,
`list_dir`, and the git tools. Their prompts also forbid describing edits as if they had been
made.

## Variants and tool sets

Two separate things narrow the tool list, and they compose.

A variant withholds tools by *capability*: `plan` cannot write, whatever the config says.
`toolSets` withholds them by *cost*: a project that never wants the git tools switches that set
off for every variant. See [tools](tools.md#tool-sets).

Both go through one function, so a withheld tool is missing from the wire and from the system
prompt together. `/tools` lists what is actually offered this turn, with the set each tool came
from.

## Thinking levels

`off`, `low`, `medium`, `high`, `max`. They map to whatever the provider actually supports:

| Level | OpenAI `reasoning_effort` | Anthropic `thinking` |
|---|---|---|
| `off` | `none` | `{ type: "disabled" }` |
| `low` | `low` | `budget_tokens: 6400` |
| `medium` | `medium` | proportional budget |
| `high` | `high` | `budget_tokens: 38400` |
| `max` | `xhigh` | maximum budget |

Verified against both wire formats rather than assumed.

Higher costs more and takes longer. `off` on a hard problem produces confident wrong
answers; `max` on a rename wastes a few cents and several seconds. The variants pick
sensible defaults, so reach for `/think` only when a specific turn needs something else.

## Overriding

`--agent deep --think low` gives you `deep`'s tools, steps, and appendix with a low thinking
budget. The override clones the preset rather than mutating it, so a later `/agent deep` in
the same session still gets `max`.

## Defaults in config

```json
{ "agent": "deep", "thinking": "high" }
```

A flag beats the config file. An unknown name fails at startup with the valid list rather
than silently falling back:

```
$ shiro --agent turbo
shiro: Unknown agent "turbo". Available: default, quick, deep, plan, review
```

## What the variant changes in the prompt

The system prompt describes only the tools actually offered, and the workflow rules adapt.
Under `plan` the model is told it has no tools that change anything and that it cannot run
commands, so it should say what to run rather than claim it passed. Under `default` it is
told which tools need approval and to verify with the project's tests.

A prompt that describes a withheld tool teaches the model to attempt calls that cannot
succeed, which is why the description is generated from the live tool set.