confidence-check

confidence-check is a skill for Claude Code, Codex from byerlikaya/claude-starter-kit. It costs 43 tokens per session (1,372 once invoked), scanned A, original, MIT.

A readiness check performed before writing substantial implementation code. It verifies whether the work already exists, fits the project, uses a confirmed API, and has a known cause and reference.

In plain words
What is it for?
Use it before starting non-trivial changes to search the codebase, inspect project guidance, verify external behavior, and gather supporting evidence.
Why use it?
It helps avoid duplicate code, unsuitable designs, and implementations based on assumptions about how an API or codebase works.

Skill for Claude CodeCodex

Written for no agent in particular: nothing here depends on one. Also seen: mentions CLAUDE.md; mentions Claude Code.

Good fit Use it before starting non-trivial changes to search the codebase, inspect project guidance, verify external behavior, and gather supporting evidence.

Compare 6 skills from other repositories ↓
Install with agentmods
npx agentmods add skills/byerlikaya/claude-starter-kit/confidence-check
Install

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.

Any agent
npx skills add byerlikaya/claude-starter-kit --skill confidence-check
Clone the repo
git clone --depth 1 https://github.com/byerlikaya/claude-starter-kit

Made for: Claude Code, Codex.

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 confidence-check

README.md
[![agentmods](https://agentmods.dev/badge/skills/byerlikaya/claude-starter-kit/confidence-check/github.svg)](https://agentmods.dev/skills/byerlikaya/claude-starter-kit/confidence-check)
Your own site
<a href="https://agentmods.dev/skills/byerlikaya/claude-starter-kit/confidence-check"><img src="https://agentmods.dev/badge/skills/byerlikaya/claude-starter-kit/confidence-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.

agentmods 80×15 button for confidence-check

Your own site · 80×15
<a href="https://agentmods.dev/skills/byerlikaya/claude-starter-kit/confidence-check"><img src="https://agentmods.dev/badge/skills/byerlikaya/claude-starter-kit/confidence-check.svg" alt="Reviewed on agentmods" width="80" height="20"></a>
Per session 43 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 1,372 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 $0.00043 $0.01372
Opus 5 $0.00022 $0.00686
Sonnet 5 $0.00009 $0.00274
Haiku 4.5 $0.00004 $0.00137

Measured 12d ago against content hash 3b123eb08240, method: parsed. Prices are Anthropic first-party input rates as of 2026-09-12, from the pricing page.

Security

Grade A, and why

confidence-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 12d 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.

claude-starter/skills/confidence-check/SKILL.md · 87 lines

How it starts

The opening of the file, as written. The whole thing — 87 lines — stays where its author put it; the contents beside it link to each section on GitHub.

Confidence Check — earn the right to start

Trigger phrases: "confidence check", "ready to implement", "before I start", "am I sure enough", "readiness"

When

Right before implementation code gets written for anything beyond a one-line change, and after the scope is clear ([[spec-planning]] / planner). Every other gate in this kit fires at the end — review, DoD, the commit approval. Those catch bad code. None of them catch good code that should never have been written: the duplicate of a helper that already exists, the pattern that fights the project's architecture, the call built against an API that behaves differently than remembered. That waste is invisible to a reviewer, because what they see is a clean diff.

The five checks

Each is answered with evidence, not with a feeling. Name what you ran or read.

# Check How it is actually answered
1 Does it already exist? Grep/Glob the codebase for the behaviour and its likely other names. A near-duplicate counts.
2 Does it fit this project? Read CLAUDE.md + the relevant project skill. Same stack, same pattern, no new dependency smuggled in.
3 Is the external claim verified? The API / library / config behaviour you are relying on: read the real docs or the installed source. Recalled API shapes are the single most common wrong assumption.
4 Is there a working reference? An existing call site in this repo, or a known-good implementation. "It should work like this" is not one.
5 Is the root cause known? For a fix: the cause, not the symptom. Unknown → this is a [[systematic-debugging]] task, not an implementation task.

The verdict is not a score

The tempting form is a weighted score with a threshold. It is theatre: with five checks and any sane bar, a single failure sinks it anyway, so the weights only decorate a decision that was already binary. So: any "no" is a stop. Say which check failed and do the one thing that answers it — search, read the doc, find the reference, debug the cause — then start. If the user wants to proceed with a known gap, that is their call to make explicitly, and it gets written down as an assumption, not swallowed.

Read the full file on GitHub · 87 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. 12d ago First seen · 87 lines · 43 tokens per session scan A 3b123eb08240

Subscribe to this mod's changes

confidence-check is a skill published in the GitHub repository byerlikaya/claude-starter-kit (22 stars, last pushed today), licensed MIT. It adds 43 tokens to every session and 1,372 once invoked, about $0.0002 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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