fable-validate-loop

fable-validate-loop is a skill for Claude Code from richkuo/rk-skills. It costs 52 tokens per session (2,257 once invoked), scanned A, original, MIT.

An automated workflow that checks whether a GitHub issue is clear, creates an implementation plan, and carries the work through code changes and pull-request review. A pull request is a proposed code change submitted for review.

In plain words
What is it for?
Use it to validate an issue, update it when needed, post a plan, implement the work, and drive its pull request toward review completion.
Why use it?
It catches unsupported or unclear issue requirements before implementation and links validation, planning, coding, and review in one run.

Skill for Claude Code

Written for Claude Code: shipped in a Claude Code plugin. Also seen: mentions CLAUDE.md; mentions subagents; mentions AGENTS.md.

Part of the rk-skills plugin — 37 skills, 1 command 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 skills/richkuo/rk-skills/fable-validate-loop
Any agent
npx skills add richkuo/rk-skills --skill fable-validate-loop
Clone the repo
git clone --depth 1 https://github.com/richkuo/rk-skills

Made for: Claude Code.

Or install rk-skills, the plugin that ships this one along with the rest of its 37 skills, 1 command.

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-validate-loop

README.md
[![agentmods](https://agentmods.dev/badge/skills/richkuo/rk-skills/fable-validate-loop.svg)](https://agentmods.dev/skills/richkuo/rk-skills/fable-validate-loop)
Your own site
<a href="https://agentmods.dev/skills/richkuo/rk-skills/fable-validate-loop"><img src="https://agentmods.dev/badge/skills/richkuo/rk-skills/fable-validate-loop.svg" alt="Measured on agentmods" height="20"></a>
Per session 52 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 2,257 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 $0.00052 $0.02257
Opus 5 $0.00026 $0.01128
Sonnet 5 $0.00010 $0.00451
Haiku 4.5 $0.00005 $0.00226

Measured 2d ago against content hash 399a3f8cecbd, method: parsed. Prices are Anthropic first-party input rates as of 2026-09-05, from the pricing page.

Security

Grade A, and why

fable-validate-loop 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 2d 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.

skills/fable-validate-loop/SKILL.md · 85 lines

How it starts

The opening of the file, as written. The whole thing — 85 lines — stays where its author put it; the contents beside it link to each section on GitHub.

fable-validate-loop

Chain fable-validate → (conditional) update issue → fableplan → work-on-issue-loop into one autonomous run: Fable 5.1 validates the issue, the main agent fixes the issue description if needed, Fable 5.1 plans the implementation (plan posted to the issue), and work-on-issue-loop implements the plan and drives the PR through review to convergence. This is fable-validate's interactive handoff made unattended — the loop reads its own verdicts and proceeds, instead of waiting for the user to reply.

Do not skip or reorder the chain. Validation gates planning (a plan built on refuted claims is wrong), and the plan gates implementation (that's the point of routing through fableplan). The only sanctioned skip is the step-4 score gate (a verdict signal of fableplan: no, which means both the title score and the recomputed score are below 71, bypasses fableplan). Every other step of each skill still runs; only the "wait for the user's reply" moments are replaced by the decision rules below.

Input

Same defaults as fable-validate: issue URL, #<N> / <N> / owner/repo#N, or nothing (defaults to the latest open issue in the current repo).

Optional targetBranch (orchestration form { issue, targetBranch } or a prose "target branch "): passed unchanged to every validate, plan, and build step in the chain, so the baseline and the PR base are that branch instead of the repo default. work-on-issue step 1 ("Target") owns its validation.

Steps

1. Run fable-validate

Invoke the fable-validate skill for the target issue (Skill tool, skill: fable-validate). Let it run fully — Fable 5.1 subagent validation, spot-check, verdict — producing the standard verdict block:

**#<N>: Update issue description? <Yes|No>**  ·  Complexity: <score>/100 — Capability <k> (Risk <r>, Uncertainty <u> — <driver>); Volume <v> (Scope <s>, Coupling <c>, Verification <x>) · fableplan: <yes|no>  ·  Scope: <OK | too large — split/umbrella/narrow>

Read the full file on GitHub · 85 lines

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. 2d ago Changed · +2 lines · +2 tokens per session 399a3f8cecbd
  2. 6d ago First seen · 83 lines · 50 tokens per session scan A 9fb29c7c12bf

Subscribe to this mod's changes

fable-validate-loop is a skill published in the GitHub repository richkuo/rk-skills (49 stars, last pushed today), licensed MIT. It adds 52 tokens to every session and 2,257 once invoked, about $0.0003 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.

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