Borrowing it
Nothing to install: this file belongs to sean-galloway/RTLDesignSherpa. Take a copy, put it at the same path in your own repository, and replace the rules that are about this project with yours.
curl -O https://raw.githubusercontent.com/sean-galloway/RTLDesignSherpa/main/.claude/skills/formal/SKILL.mdgit clone --depth 1 https://github.com/sean-galloway/RTLDesignSherpaWrote 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/sean-galloway/rtldesignsherpa/formal)<a href="https://agentmods.dev/skills/sean-galloway/rtldesignsherpa/formal"><img src="https://agentmods.dev/badge/skills/sean-galloway/rtldesignsherpa/formal/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/sean-galloway/rtldesignsherpa/formal"><img src="https://agentmods.dev/badge/skills/sean-galloway/rtldesignsherpa/formal.svg" alt="Reviewed on agentmods" width="80" height="20"></a>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 | $0.00057 | $0.00178 |
| Opus 5 | $0.00028 | $0.00089 |
| Sonnet 5 | $0.00011 | $0.00036 |
| Haiku 4.5 | $0.00006 | $0.00018 |
Grade A, and why
formal 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 10d 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.
What it actually says
formal
READ FIRST: vault/handbook/dv/formal.md (the handbook is the repo's memory; this skill is the signpost). sv2v deletes assertions without --exclude=Assert; mutation-check every property; watch the vacuity traps; BMC-25 is not induction.
The handbook root is vault/handbook/INDEX.md - design/, dv/, fpga/ areas, atomic notes, wikilinked. When you learn a durable lesson in this domain, ADD IT TO THE HANDBOOK NOTE, not to this skill.
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.
- 10d ago First seen · 14 lines · 57 tokens per session scan A 6f793f1b1485
formal is a skill published in the GitHub repository sean-galloway/RTLDesignSherpa (23 stars, last pushed today), licensed MIT. It adds 57 tokens to every session and 178 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.
Other skills, from other repositories
codec-conformance-eval
Evaluate C ref-model decoder against JVET/JCTVC conformance bitstreams (bitexact/MD5) — 'decoder conformance'; C-level, not RTL (rtl-conformance-test).
bfm-develop
Builds Phase 3 SystemC TLM-2.0 bus functional models with AMBA (AXI/AHB/APB) support. Use for 'develop BFM', 'SystemC TLM model', 'bus functional model'.
rat-p4p5-impl-verify-policy
Internal reference: rat p4p5 impl verify policy (agent-loaded; do not invoke).
ref-model
Builds Phase 2 golden C reference model with bitexact conformance and bandwidth estimation. Use for 'build reference model', 'C ref model', 'golden model'.
rtl-conformance-test
Final codec standards compliance gate: bitexact RTL bitstream check against JM/HM reference. Triggers: 'conformance test', 'H.264/H.265 conformance'.
rtl-lint-check
Lint RTL with Verilator, Verible, and slang; report-only quick check for 'run lint', pre-commit, or phase-gate verification (no fixing).