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 skills add axiomantic/spellbook --skill reviewing-impl-plansgit clone --depth 1 https://github.com/axiomantic/spellbookWrote 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.
[](https://agentmods.dev/skills/axiomantic/spellbook/reviewing-impl-plans)<a href="https://agentmods.dev/skills/axiomantic/spellbook/reviewing-impl-plans"><img src="https://agentmods.dev/badge/skills/axiomantic/spellbook/reviewing-impl-plans/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.
<a href="https://agentmods.dev/skills/axiomantic/spellbook/reviewing-impl-plans"><img src="https://agentmods.dev/badge/skills/axiomantic/spellbook/reviewing-impl-plans.svg" alt="Reviewed on agentmods" width="80" height="20"></a>- NVIDIA SkillSpector pass
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.
| Model | Per session | Once invoked |
|---|---|---|
| Fable 5.1 | $0.00077 | $0.02013 |
| Opus 5 | $0.00039 | $0.01007 |
| Sonnet 5 | $0.00015 | $0.00403 |
| Haiku 4.5 | $0.00008 | $0.00201 |
Grade A, and why
reviewing-impl-plans 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 — 181 lines — stays where its author put it; the contents beside it link to each section on GitHub.
Every gap you miss becomes hours of wasted work downstream. Agents will execute this plan trusting your review caught the problems. That trust is earned by thoroughness, not speed. Your career-defining reviews prevent catastrophic integration failures before they happen.
<CRITICAL_INSTRUCTION> This review protects against implementation failures from underspecified plans.
You MUST:
- Compare plan to parent design document (if exists)
- Verify every interface between parallel work streams is explicitly specified
- Identify every point where executing agents would have to guess or invent
- Verify existing code behaviors cite source, not method name inference
An implementation plan that sounds organized but lacks interface contracts creates incompatible components. </CRITICAL_INSTRUCTION>
Invariant Principles
-
Parallel agents hallucinate incompatible interfaces when contracts are implicit. Every handoff point must specify exact data shapes, protocols, error formats.
-
Assumed behavior causes debugging loops. Plans referencing existing code must cite source, not infer from method names. Parameters like
partial=Trueorstrict=Falseare fabricated until verified. -
Implementation plans must exceed design doc specificity. Design says "user endpoint"; impl plan specifies method, path, request/response schema, error codes, auth mechanism.
-
Test quality claims require verification. Passing tests prove nothing without auditing-green-mirage. Test failures require systematic-debugging, not ad-hoc fixes.
Inputs
| Input | Required | Description |
|---|---|---|
impl_plan |
Yes | Path to or content of the implementation plan to review |
design_doc |
No | Path to parent design document for comparison |
codebase_root |
No | Project root for verifying existing code behavior references |
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 Changed · -87 lines 1581f1e3f558
- 5d ago First seen · 268 lines · 77 tokens per session scan A 00f350231f75
reviewing-impl-plans is a skill published in the GitHub repository axiomantic/spellbook (10 stars, last pushed yesterday), licensed MIT. It adds 77 tokens to every session and 2,013 once invoked, about $0.0004 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 2026-09-03.
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