Borrowing it
Nothing to install: this file belongs to mtarcure/claude-vibe-squad. 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/mtarcure/claude-vibe-squad/main/.agents/skills/interface-ambiguity-check/SKILL.mdgit clone --depth 1 https://github.com/mtarcure/claude-vibe-squadWrote 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/mtarcure/claude-vibe-squad/interface-ambiguity-check)<a href="https://agentmods.dev/skills/mtarcure/claude-vibe-squad/interface-ambiguity-check"><img src="https://agentmods.dev/badge/skills/mtarcure/claude-vibe-squad/interface-ambiguity-check/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/mtarcure/claude-vibe-squad/interface-ambiguity-check"><img src="https://agentmods.dev/badge/skills/mtarcure/claude-vibe-squad/interface-ambiguity-check.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 | $0.00088 | $0.00949 |
| Opus 5 | $0.00044 | $0.00475 |
| Sonnet 5 | $0.00018 | $0.00190 |
| Haiku 4.5 | $0.00009 | $0.00095 |
Grade A, and why
interface-ambiguity-check 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.
How it starts
The opening of the file, as written. The whole thing — 49 lines — stays where its author put it; the contents beside it link to each section on GitHub.
Interface Ambiguity Check
Two parties meeting at a boundary each hold a private interpretation of it. Before writing code against an interface, make every load-bearing assumption explicit, classify it as documented, observed, or guessed — and eliminate the guesses.
When to use
- Implementing against an API, schema, TSV/JSON format, function signature, or protocol authored by someone else (including a past task).
- Two independently-built components are about to integrate.
- A packet says "integrate with X" or "consume Y's output" without a contract document.
Inputs
- The interface artifact: schema, header row, signature, endpoint doc, example payload.
- Real producer/consumer behavior: actual payloads, actual call sites, the parser's source.
Steps
- List every element crossing the boundary: each field, parameter, return value, status code, file, and side effect.
- Run each element through the ambiguity battery: type and units; required vs optional; null vs empty vs absent; ordering and uniqueness guarantees; case, encoding, and delimiter rules; error signaling (exception, code, sentinel, silence); idempotency and retry semantics; which side validates; versioning and evolution rules.
- Classify each answer: documented (cite where), observed (cite the real payload, call site, or parser line you inspected), or assumed (unpinned).
- Pin every load-bearing assumption: read the counterpart's source, inspect a real sample, or run a cheap probe. When the boundary's owner must decide — surface the question (in a packet context:
## NEEDS FROM CHRONO, orblockedper specialist rules) instead of implementing a guess whose wrong answer is expensive to unwind. - When documentation and observed behavior disagree, the observed behavior wins for implementation — and the disagreement itself is a finding to report, not to silently absorb.
- Encode pinned answers where the machine can hold them: a strict parser, an assertion, a test that uses a real captured sample rather than a hand-invented one.
- Record deliberately unpinned residuals as named risks in the artifact, with the trigger that would surface each.
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 · 49 lines · 88 tokens per session scan A 86f0bda607a8
interface-ambiguity-check is a skill published in the GitHub repository mtarcure/claude-vibe-squad (122 stars, last pushed yesterday), licensed MIT. It adds 88 tokens to every session and 949 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 2026-08-30.
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