c-check

c-check is a skill for Claude Code from sentasity/cadence. It costs 100 tokens per session (2,951 once invoked), scanned A, original, MIT.

A review tool for checking whether a design or implementation plan makes sense as a whole. It looks for missing details, contradictions, unsupported assumptions, and scope that has grown beyond the original task.

In plain words
What is it for?
Use it to review a complete design, plan, or individual document for accuracy, consistency, completeness, and practical feasibility.
Why use it?
It catches problems in the proposed approach before they become coding problems. For plans, it also checks that referenced files, symbols, and imports exist.

Skill for Claude Code

Written for Claude Code: ${CLAUDE_PLUGIN_ROOT} variable. Also seen: mentions subagents; names the AskUserQuestion tool.

Runs only inside its plugin — its command needs a path that Claude Code sets for a plugin’s own hooks and for nothing else. Install the plugin, not this.

Part of the cadence plugin — 11 skills, 5 agents, 1 hook shipped together

Good fit Use it to review a complete design, plan, or individual document for accuracy, consistency, completeness, and practical feasibility.

Compare 6 skills from other repositories ↓
Install

Getting it into your agent

This one installs as part of its plugin. Adding the marketplace and installing the plugin brings it with everything else the plugin ships.

Claude Code
/plugin marketplace add sentasity/cadence
Claude Code
/plugin install cadence

Made for: Claude Code.

Or install cadence, the plugin that ships this one along with the rest of its 11 skills, 5 agents, 1 hook.

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 c-check

README.md
[![agentmods](https://agentmods.dev/badge/skills/sentasity/cadence/c-check.svg)](https://agentmods.dev/skills/sentasity/cadence/c-check)
Your own site
<a href="https://agentmods.dev/skills/sentasity/cadence/c-check"><img src="https://agentmods.dev/badge/skills/sentasity/cadence/c-check.svg" alt="Measured on agentmods" height="20"></a>
Per session 100 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 2,951 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 $0.00100 $0.02951
Opus 5 $0.00050 $0.01476
Sonnet 5 $0.00020 $0.00590
Haiku 4.5 $0.00010 $0.00295

Measured 7d ago against content hash 00e9b8b1cdd1, method: parsed. Prices are Anthropic first-party input rates as of 2026-09-07, from the pricing page.

Security

Grade A, and why

c-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 7d 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/c-check/SKILL.md · 172 lines

How it starts

The opening of the file, as written. The whole thing — 172 lines — stays where its author put it; the contents beside it link to each section on GitHub.

/c-check

You review designs and plans for substance — does this make sense, does it hang together, are there gaps, are there silent assumptions that won't survive contact with reality. You do NOT review code quality (that's /c-find-bugs). One exception: when the target is a plan, you narrowly read code to verify cited paths/symbols/imports exist — enforcing /c-plan's "Codebase verification" rule from the outside.

Invocation forms

  • /c-check <design-folder-path> — review full design.
  • /c-check <plan-folder-path> — review full plan.
  • /c-check <single-doc-path> — review one child doc in isolation.
  • /c-check --format <path> — also run Cadence format compliance.
  • /c-check --any <path> — accept paths outside Cadence's expected folder structure (e.g. imported designs from elsewhere).

Entry contract

Refuses when: the target does not resolve to an artifact; OR the target is in a Cadence-managed location and the resolved artifact lacks the expected structure (no overview, missing frontmatter) — check existence and structure via skills/_shared/storage-resolution.md (artifact_exists) in the active backend — unless --any is set.

Default mode: substance checks

Each check runs as its own sub-agent in parallel (via Task tool). Each receives the target doc(s) + the check's specific prompt.

Check What it asks
Accuracy Do the claims in this doc match related artifacts (linked design ↔ plan, internal cross-references)?
Internal consistency Do sections contradict each other? Do decisions in the overview match what children actually say?
Completeness Are there obvious gaps — missing failure modes, undefined terms, untouched concerns (security, observability, perf)?
Hidden assumptions What is the doc taking for granted that won't be true? (e.g. "user is logged in" without saying when login happens.)
Scope discipline Does the design/plan stay within brainstormed scope, or has it crept?
Internal logic Logical errors in proposed flow — race conditions, infinite loops, ordering violations.
Open-questions check (Invariant 1) Any callouts that read like open questions ("should we…", "we might…", "TBD")?
Codebase verification (plans only) Do the file paths, line ranges, symbols, and imports cited in the plan exist in the current code? Per /c-plan's "Codebase verification" rule: ls/Read every Modify and Test path; Read cited line ranges; grep every symbol and import path; check codebase conventions match. Citation that doesn't resolve = Critical (plan unexecutable as written). Range drift that still points at the right function = Important. Convention mismatch (_lambda vs lambda_, etc.) = Important. Skipped for designs.
DAG soundness (plans only) Do two tasks that reference each other's Touches: files or declared symbols have a Depends: edge between them? A missing edge between mutually-referencing tasks is a parallel-execution hazard the Touches: guard can't catch — flag as Important (the engine could co-schedule them and the dependent task would run against absent code). Also flag any Depends: cycle as Critical (plan unexecutable). Skipped for designs.

Read the full file on GitHub · 172 lines

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. 7d ago First seen · 172 lines · 0 tokens per session scan A 00e9b8b1cdd1

Subscribe to this mod's changes

c-check is a skill published in the GitHub repository sentasity/cadence (1 stars, last pushed 12d ago), licensed MIT. It adds 100 tokens to every session and 2,951 once invoked, about $0.0005 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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