fable-reviewer

fable-reviewer is an agent for Claude Code from Lykhoyda/ask-llm. It costs 32 tokens per session (445 once invoked), scanned A, original, MIT.

An independent, read-only code-review add-on that asks the Fable model to examine supplied changes and report source-verified correctness problems. It is designed to keep reviews focused on high-confidence findings.

In plain words
What is it for?
Use it to review a Git diff, inspect nearby changed code and applicable project instructions, and identify concrete bugs, security risks, data loss, concurrency issues, or compatibility failures.
Why use it?
It checks proposed issues against the actual code and excludes style preferences, speculation, pre-existing problems, and issues handled by automated checks.

Agent for Claude Code

Written for Claude Code: effort in frontmatter. Also seen: model in frontmatter; mentions CLAUDE.md; mentions subagents.

Part of the ask-llm plugin — 18 skills, 9 agents, 5 hooks, 1 MCP server shipped together

Install

Getting it into your agent

One page per mod, every tool's command on it. A separate URL per tool would split the same page into five that compete with each other.

agentmods
npx agentmods add agents/lykhoyda/ask-llm/fable-reviewer
Clone the repo
git clone --depth 1 https://github.com/Lykhoyda/ask-llm

Made for: Claude Code.

Or install ask-llm, the plugin that ships this one along with the rest of its 18 skills, 9 agents, 5 hooks, 1 MCP server.

Wrote this? Show the measurements

A badge with what this costs and how it scanned, read live from this page, so it follows the numbers instead of freezing them. Markdown for a README, HTML for a documentation site or a project page.

agentmods badge for fable-reviewer

README.md
[![agentmods](https://agentmods.dev/badge/agents/lykhoyda/ask-llm/fable-reviewer.svg)](https://agentmods.dev/agents/lykhoyda/ask-llm/fable-reviewer)
Your own site
<a href="https://agentmods.dev/agents/lykhoyda/ask-llm/fable-reviewer"><img src="https://agentmods.dev/badge/agents/lykhoyda/ask-llm/fable-reviewer.svg" alt="Measured on agentmods" height="20"></a>
Per session 32 Only the description is in the session, so the agent can decide to use it. The body loads when it is invoked.
When invoked 445 The whole file, excluding the scripts and references it only reads on demand.
Security scan A 0 findings. Scan, not verified.
Origin original No closer match found in the catalogue.
Token cost

What it costs to keep this loaded

Counted locally with the o200k_base tokenizer, which is exact for GPT models; Claude uses its own tokenizer and its counts differ. Treat this as one consistent yardstick across the catalogue rather than a bill. Prices are per million input tokens.

ModelPer sessionOnce invoked
Fable 5.1 $0.00032 $0.00445
Opus 5 $0.00016 $0.00222
Sonnet 5 $0.00006 $0.00089
Haiku 4.5 $0.00003 $0.00044

Measured 6d ago against content hash 08abff7ae5be, method: parsed. Prices are Anthropic first-party input rates as of 2026-09-06, from the pricing page.

Security

Grade A, and why

fable-reviewer scanned grade A with 0 findings against 26 rules in 11 categories — prompt injection, anti-refusal, data exfiltration, privilege escalation, supply chain, agent snooping, system-prompt leakage, SSRF and excessive agency — measured 6d ago.

A static scan of the body, not an audit. Every finding is printed with the line that produced it so you can judge whether it matters here. A mod is markdown that instructs an agent; that is exactly why what it instructs is worth reading.

Nothing flagged

None of the 26 patterns this scan looks for appear in this file: no shell pipes, no recursive deletes, no credential paths, no hidden text, no instruction-override or anti-refusal phrasing, no agent-config snooping. That is not a guarantee, it is the absence of the things that are checkable.

packages/claude-plugin/agents/fable-reviewer.md · 45 lines

What it actually says

Portable contract

Review only the supplied changes in a read-only independent Fable context. Validate every candidate against source, require concrete file/line evidence, and report only high-confidence correctness findings.

Claude Code adapter

The frontmatter and detailed implementation below define Claude Code subagent execution. Other hosts must ignore this adapter and use only the portable contract above.

You are a senior software engineer performing a precision-first code review. Analyze the changes yourself; do not delegate to another model or provider.

Review contract

  1. Inspect git diff and git diff --cached. Review changed code only.
  2. Read each affected file around the changed lines. Apply the nearest CLAUDE.md instructions and inspect any ADR explicitly cited by the code.
  3. Look for concrete correctness, security, data-loss, concurrency, resource-lifecycle, and compatibility failures.
  4. Do not report style preferences, speculative improvements, pre-existing issues, or problems already guaranteed to be caught by the configured linter/type checker.
  5. For every candidate, trace a specific reproduction path against the current source. Drop it when the path does not hold or the behavior is documented as intentional.
  6. Report only findings with confidence of at least 80/100. Never invent findings to fill a report.

Output

Lead with the highest-severity finding. For every surviving issue include severity (BLOCKING, IMPORTANT, or ADVISORY), confidence, file and line, failure mode, reproduction conditions, and the smallest concrete fix. State clearly when no high-confidence findings survive validation.

You have no edit tools. Remain read-only.

Changes

What this file has done since we first saw it

Hashed on every crawl. A supply-chain change to an agent config is a question of when, not whether, so the history is kept rather than the latest state alone.

  1. 6d ago First seen · 45 lines · 32 tokens per session scan A 08abff7ae5be

Subscribe to this mod's changes

fable-reviewer is an agent published in the GitHub repository Lykhoyda/ask-llm (17 stars, last pushed 3d ago), licensed MIT. It adds 32 tokens to every session and 445 once invoked, about $0.0002 per session on Opus 5. A static security scan graded it A with 0 findings. No closer match exists in the catalogue, so it is treated as the original; first seen 2026-08-30.

Related

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