fable-verify

fable-verify is a skill for Claude Code, Codex from imMamdouhaboammar/get-fable. It costs 119 tokens per session (1,789 once invoked), scanned A, original, MIT.

A verification skill that tries to disprove a software implementation using fresh evidence from tests, builds, type checks, and runtime checks. Different checks cover different risks, so a successful build alone does not prove that the program works correctly.

In plain words
What is it for?
Use it before declaring work complete, after code changes, or at a review or release gate where functional, integration, packaging, or runtime behavior must be checked.
Why use it?
It prevents completion claims from relying on stale or incomplete evidence and matches each changed area with checks that can reveal failures.

Skill for Claude CodeCodex

Written for Claude Code and Codex: shipped in a Claude Code plugin, but also agents/openai.yaml present.

Part of the get-fable plugin — 78 skills, 1 agent, 5 hooks shipped together

Good fit Use it before declaring work complete, after code changes, or at a review or release gate where functional, integration, packaging, or runtime behavior must be checked.

Compare 6 skills from other repositories ↓
Install with agentmods
npx agentmods add skills/immamdouhaboammar/get-fable/fable-verify
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.

Any agent
npx skills add imMamdouhaboammar/get-fable --skill fable-verify
Clone the repo
git clone --depth 1 https://github.com/imMamdouhaboammar/get-fable

Made for: Claude Code, Codex.

Or install get-fable, the plugin that ships this one along with the rest of its 78 skills, 1 agent, 5 hooks.

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-verify

README.md
[![agentmods](https://agentmods.dev/badge/skills/immamdouhaboammar/get-fable/fable-verify/github.svg)](https://agentmods.dev/skills/immamdouhaboammar/get-fable/fable-verify)
Your own site
<a href="https://agentmods.dev/skills/immamdouhaboammar/get-fable/fable-verify"><img src="https://agentmods.dev/badge/skills/immamdouhaboammar/get-fable/fable-verify/github.svg" alt="Measured on agentmods" height="20"></a>

Or the 80×15 button, for a site that already has a row of RSS and ATOM ones. Only the verdict fits; the numbers stay here.

agentmods 80×15 button for fable-verify

Your own site · 80×15
<a href="https://agentmods.dev/skills/immamdouhaboammar/get-fable/fable-verify"><img src="https://agentmods.dev/badge/skills/immamdouhaboammar/get-fable/fable-verify.svg" alt="Reviewed on agentmods" width="80" height="20"></a>
Per session 119 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 1,789 The whole file, excluding the scripts and references it only reads on demand.
Security scan A 0 findings. A grade says what 26 rules found in the file — not that it is safe.
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 $0.00119 $0.01789
Opus 5 $0.00060 $0.00894
Sonnet 5 $0.00024 $0.00358
Haiku 4.5 $0.00012 $0.00179

Measured 6d ago against content hash a57790355485, method: parsed. Prices are Anthropic first-party input rates as of 2026-09-11, from the pricing page.

Security

Grade A, and why

fable-verify 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.

skills/fable-verify/SKILL.md · 208 lines

How it starts

The opening of the file, as written. The whole thing — 208 lines — stays where its author put it; the contents beside it link to each section on GitHub.

Fable Verify

Try to prove the implementation wrong, then report only the claims that survive fresh evidence.

Mission

Verification is not "run the test suite." It is coverage of changed risk with evidence that is both relevant and fresh.

A green command proves only what it actually exercised. Build success does not prove runtime behavior. Security success does not prove functional correctness. Unit success does not prove a packaging or integration path. Old evidence does not prove a newer mutation.

Activate When

  • implementation or repair is ready for independent proof;
  • a completion claim needs fresh evidence;
  • a review/release gate requires test/build/runtime evidence;
  • stale evidence must be refreshed after mutation;
  • the suspected regression surface spans more than the focused TDD test.

Do Not Activate When

  • writing the implementation (fable-execute/fable-tdd);
  • deciding architecture (fable-plan);
  • reviewing design/maintainability from the diff (fable-review);
  • diagnosing repeated confusing failures (fable-recover).

Risk Classification

Map each changed surface to the evidence capable of falsifying it.

Changed surface Typical evidence
pure behavior focused unit/property + affected suite
cross-module contract integration/contract test
public CLI/API invocation/smoke + contract tests
build/export/package build + package/clean-install smoke
persistence/migration integration + migration/compatibility fixtures
async/concurrency deterministic ordering/stress supplement
config/feature flag tests under relevant config branches
browser/UI component/integration/E2E as appropriate
security boundary security-specific checks plus functional evidence
performance-sensitive path targeted measurement when requirement exists

Verification Protocol

Stage 1 — Read the diff and execution packet

Do not choose commands from habit alone. Identify:

  • behavior changed;
  • files/contracts touched;
  • tests added/changed;
  • generated/package/config surfaces;
  • residual risks from implementation;
  • current mutation generation.

Read the full file on GitHub · 208 lines

Files

What ships with it

8 files beside SKILL.md in the same directory: the scripts, references and assets a skill reads on demand. Not counted in the per-session cost; read them before you install if any of them is executable.

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 · 208 lines · 119 tokens per session scan A a57790355485

Subscribe to this mod's changes

fable-verify is a skill published in the GitHub repository imMamdouhaboammar/get-fable (4 stars, last pushed yesterday), licensed MIT. It adds 119 tokens to every session and 1,789 once invoked, about $0.0006 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 2026-09-05.

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