A working rule that requires every claim about code or configuration to include a real check, such as a test, build, command, or file inspection. If a check cannot be run, the result must be labeled unverified.

Use it when implementing, fixing, refactoring, debugging, deploying, or verifying code and configuration.

It reduces false claims that a fix works when nobody has actually tested it. The command and its output provide evidence for the result.

prove-it — Skill for Claude Code and Codex by daronthedragon

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 daronthedragon/skillsmith --skill prove-it

Clone the repo

git clone --depth 1 https://github.com/daronthedragon/skillsmith

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.

README.md

[![agentmods](https://agentmods.dev/badge/skills/daronthedragon/skillsmith/prove-it/github.svg)](https://agentmods.dev/skills/daronthedragon/skillsmith/prove-it)

Your own site

<a href="https://agentmods.dev/skills/daronthedragon/skillsmith/prove-it"><img src="https://agentmods.dev/badge/skills/daronthedragon/skillsmith/prove-it/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.

Your own site · 80×15

<a href="https://agentmods.dev/skills/daronthedragon/skillsmith/prove-it"><img src="https://agentmods.dev/badge/skills/daronthedragon/skillsmith/prove-it.svg" alt="Reviewed on agentmods" width="80" height="20"></a>

Per session 113 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.

When invoked 803 The whole file, excluding the scripts and references it only reads on demand.

Security scan A 1 finding. 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.

Model	Per session	Once invoked
Fable 5.1	$0.00113	$0.00803
Opus 5	$0.00056	$0.00402
Sonnet 5	$0.00023	$0.00161
Haiku 4.5	$0.00011	$0.00080

Measured 12d ago against content hash f980857cc298, method: parsed. Prices are Anthropic first-party input rates as of 2026-09-12, from the pricing page.

Security

Grade A, and why

prove-it scanned grade A with 1 finding 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.

Makes network callslowCapability

Not a fault in itself. Listed so you know the mod talks to something, and to what.

1. Name what would prove the claim: a test command, a build, a curl, a script,

examples/prove-it/SKILL.md · 79 lines

How it starts

The opening of the file, as written. The whole thing — 79 lines — stays where its author put it; the contents beside it link to each section on GitHub.

Prove It

An agent's most expensive failure is a confident claim that turns out false: "fixed", "should work now", "the contributor list is clean" - said before anyone looked. The cost is not the bug; it is the user trusting the claim, moving on, and finding out later. This skill makes every claim carry its receipt.

Persistence

ACTIVE EVERY RESPONSE once triggered. Still active when the change feels too small to test. Off only when the user says "stop prove-it" or "normal mode".

Procedure

Run this before every completion message, in order.

Name what would prove the claim: a test command, a build, a curl, a script, opening the page, reading the file back. If nothing can prove it, go to 5.
Run it. Do not describe what running it would show - run it.
Read the real output. If it contradicts the claim, the claim is false; fix the work, not the wording, and return to 1.
In the completion message, paste the command and the decisive lines of its output next to the claim it supports. One receipt per claim.
If a claim cannot be run - no key, no network, no access - write the word "unverified" beside it and say what would verify it. Never upgrade "unverified" to "works" by rephrasing.
Before sending, scan the message for the phrases in Rules. Delete or replace each one with a receipt or with "unverified".

Rules

The phrases "should work", "looks correct", "this will", "I believe this fixes", and "appears to" do not appear in a completion message. Each is replaced by a command and its output, or by "unverified".
A claim about a remote state (a web page, a repo, an API, a deployment) is verified by reading that remote state, not the local files that produced it. Local clean and remote clean are different facts.
One check per claim. Verifying the API does not verify the page; verifying the commit message does not verify the contributors panel.
When a check fails, the completion message reports the failure and its output. Silence about a failed check is a false claim.
The receipt is the decisive lines, not a log dump. Trim to what settles it.

Read the full file on GitHub · 79 lines

Files

What ships with it

4 files beside SKILL.md in the same directory: the scripts, references and assets a skill reads on demand. Not counted in the per-session cost; read them before you install if any of them is executable.

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.

12d ago First seen · 79 lines · 113 tokens per session scan A f980857cc298

Subscribe to this mod's changes

prove-it is a skill published in the GitHub repository daronthedragon/skillsmith (2 stars, last pushed 23d ago), licensed MIT. It adds 113 tokens to every session and 803 once invoked, about $0.0006 per session on Opus 5. A static security scan graded it A with 1 finding (makes network calls). No closer match exists in the catalogue, so it is treated as the original; first seen 2026-08-31.

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