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.
npx skills add jtsang4/efficient-coding --skill prove-itgit clone --depth 1 https://github.com/jtsang4/efficient-codingWrote 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/jtsang4/efficient-coding/prove-it)<a href="https://agentmods.dev/skills/jtsang4/efficient-coding/prove-it"><img src="https://agentmods.dev/badge/skills/jtsang4/efficient-coding/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.
<a href="https://agentmods.dev/skills/jtsang4/efficient-coding/prove-it"><img src="https://agentmods.dev/badge/skills/jtsang4/efficient-coding/prove-it.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 | $0.00092 | $0.02145 |
| Opus 5.5 | $0.00037 | $0.00858 |
| Sonnet 5.5 | $0.00018 | $0.00429 |
| Haiku 4.5 | $0.00009 | $0.00215 |
Grade A, and why
prove-it 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 1mo 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 — 111 lines — stays where its author put it; the contents beside it link to each section on GitHub.
Prove It
You proposed the idea; from here on, stop defending it. Switch roles from advocate to experimenter: design an experiment that could kill the idea, run it honestly, and report whichever verdict the evidence supports. "Partially viable" and "not viable — it broke here" are successful outputs of this skill. A proof that cannot fail is not a proof.
The audience for every piece of evidence is the user. Narrative is not evidence. Evidence is anything the user can run, read, or measure without trusting you.
The unit of proof is the claim, not the idea. Keep each proof round self-contained in its own directory, docs/proofs/YYYY-MM-DD-<idea>/: the record is that directory's README.md (created from references/proof-record-template.md), and everything the verdicts point to lives in evidence/ beside it. Successive proofs sit side by side instead of interleaving. Work through the phases in order.
1. Extract the Claims
Decompose the idea into explicit claims and classify each:
- capability — X can be built or done at all.
- quality — X is simpler, faster, safer, or cheaper than the current baseline.
- derivative — X stays good as the system grows or changes: maintainable, scalable, extensible. These are claims about a cost curve, not a point.
- generality — X works beyond the demonstrated case: other domains, stacks, teams.
Mark the killer claims: the ones whose falsity kills the idea. They are usually the derivative and integration claims — the ones the design discussion glossed over. Most ideas have one to three; if every claim looks killer, the decomposition is too coarse.
Present the claim list to the user and confirm the killer set before designing anything. The user knows hostilities you do not.
2. Design the Experiment
Choose the apparatus by evidence strength against the killer claims, never by ease of construction:
- Brownfield retrofit — implement the idea inside an existing real project. Prefer this whenever the idea claims to apply to existing systems: reality supplies legacy constraints, dirty data, and integration friction for free.
- Greenfield build — a new minimal-but-sufficient project. Right for paradigm-level ideas with nothing to retrofit into; hostility must then be manufactured deliberately, or the apparatus slides into a toy.
- Reference problem — implement a well-known non-trivial problem in the new approach. Public recognition of the problem's difficulty prevents cherry-picking.
- Targeted spike or benchmark — when one subproblem carries all the risk, attacking it directly beats building everything around it.
What ships with it
3 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.
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.
- 1mo ago First seen · 111 lines · 92 tokens per session scan A c560ad124c1e
prove-it is a skill published in the GitHub repository jtsang4/efficient-coding (2 stars, last pushed 8d ago), licensed MIT. It adds 92 tokens to every session and 2,145 once invoked, about $0.0004 per session on Opus 5.5. 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 2026-09-04.
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