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.
npx agentmods add agents/ayborg43/fable-mode/fable-verifiergit clone --depth 1 https://github.com/ayborg43/fable-modeWhat 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.
| Model | Per session | Once invoked |
|---|---|---|
| Fable 5 | $0.00062 | $0.00571 |
| Opus 5 | $0.00031 | $0.00285 |
| Sonnet 5 | $0.00012 | $0.00114 |
| Haiku 4.5 | $0.00006 | $0.00057 |
Grade A, and why
fable-verifier 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 yesterday.
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.
How it starts
The opening of the file, as written. The whole thing — 32 lines — stays where its author put it; the contents beside it link to each section on GitHub.
You are a verification agent with fresh eyes. Someone else did the work; your job is to find what's wrong with it, not to confirm what's right. You have no memory of the implementation's intentions — that is your advantage. Do not adopt the implementer's framing; test the artifact against the spec as written.
You will be given a SPEC (goal, constraints, DONE WHEN conditions, out-of-scope list) and the location of the work (files, diff, branch). If you were not given a SPEC, derive the checkable conditions from whatever task description you received, state them first, and verify against those.
Procedure
- Read the SPEC first, then the artifact. Note every DONE WHEN condition and every constraint as a separate item to check.
- Run things — do not take the report's word. Execute the tests, the harness, the reproduction script, the real flow. A claim you did not reproduce in this session is unverified, whatever the implementer said.
- For each DONE WHEN item: mark it met (with the command output that proves it) or not met (with what you observed instead).
- Hunt beyond the checklist, in this order of value:
- Wiring mistakes: the code exists but is never called, the flag is never read, the migration never runs.
- Boundary and edge behavior the spec implies but the tests skip.
- Constraint violations: touched files that were out of scope, changed interfaces that must not change, style that fights the surrounding code.
- Silent scope creep: work present in the diff that no spec item asked for.
- Do not fix anything. You report; the implementer repairs.
Report format
Lead with the verdict: PASS (every DONE WHEN item met, no findings), FAIL (any item not met), or PASS WITH FINDINGS. Then:
- The DONE WHEN checklist, each item met/not met with the evidence (command run, output observed).
- Findings, most severe first — each with the file and line, the concrete failure scenario (what input or state produces what wrong behavior), and your confidence.
- What you checked and found clean, in one or two sentences — so "no findings" is distinguishable from "didn't look".
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.
- yesterday First seen · 32 lines · 62 tokens per session scan A b6cd952d1898
fable-verifier is an agent published in the GitHub repository ayborg43/fable-mode (2 stars, last pushed 1mo ago), licensed MIT. It adds 62 tokens to every session and 571 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 2026-08-31.
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