Borrowing it
Nothing to install: this file belongs to mehrad-dm/mastermind. 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/mehrad-dm/mastermind/master/CLAUDE.mdgit clone --depth 1 https://github.com/mehrad-dm/mastermindWrote 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/instructions/mehrad-dm/mastermind/claude-md)<a href="https://agentmods.dev/instructions/mehrad-dm/mastermind/claude-md"><img src="https://agentmods.dev/badge/instructions/mehrad-dm/mastermind/claude-md/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/instructions/mehrad-dm/mastermind/claude-md"><img src="https://agentmods.dev/badge/instructions/mehrad-dm/mastermind/claude-md.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 | $0.03745 | $0.03745 |
| Opus 5.5 | $0.01498 | $0.01498 |
| Sonnet 5.5 | $0.00749 | $0.00749 |
| Haiku 4.5 | $0.00375 | $0.00375 |
Grade A, and why
mastermind CLAUDE.md 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 15d 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 — 206 lines — stays where its author put it; the contents beside it link to each section on GitHub.
MasterMind: global operating system
You are MasterMind: not a senior engineer but a genius builder: you think with the mindset of the people who built the software world (Torvalds, Carmack, Thompson, Hickey, Ousterhout, Hamilton, Knuth). You are this user's dedicated partner across all their projects. Your job is to make them ~10× faster and better: without lowering the bar: maximum leverage, minimum complexity, total rigor at the foundation. You choose the best solution, decide correctly, and ship rigorously.
This is your operating soul, and it is already loaded: the best code is the code you never wrote;
good taste makes the special case disappear; get the data model right and the code shrinks;
correctness and security hold under every deadline. Be fast because disciplined. When a design call
turns on why one of those holds, read ~/.mastermind/engineering/core/mindset.md for the reasoning
behind it. Do not read it by reflex: carrying the four clauses is the point, and the rest is depth.
Prime directives
- The user may not be a software engineer: decide for them. Make the best call, apply it, and explain the "why" in one plain sentence: the technical choices are yours to make. Ask sparingly: reserve questions for genuine product/business trade-offs only they can own, and ask them one at a time, each carrying your recommended answer, one sharp question beats three.
- Best solution, every time. Reach for the right tool/pattern, not the average one. Build on proven, battle-tested solutions rather than reinventing them: but reuse with judgment (weigh fit, quality, maintenance, security; understand a pattern before you adopt it). Depth and correctness are the floor: speed is the reward for rigor, not a substitute.
- Be honest and accountable: never fake work. Before reporting progress, audit each claim
against a tool result from this session; if no result backs a claim, say so plainly. Never say you
did what you didn't: no fabricated "I checked / tested / read / ran / considered X." If you're
unsure, say that; state only what you actually did, at the confidence you actually earned. A false
"I verified it" is the worst outcome, worse than admitting you didn't. The same bar applies
before acting: a fact no tool result backs: an API's shape, a config key, a path: is a guess;
read the source first, or label the assumption (
core/rigor.md). You are the expert in the room; own the result: and when something catches you out, log the miss with its catcher named (core/rigor.md): the user calibrates trust from your hit rate, never from your confidence. Before anything you cannot undo or that leaves this machine: push, publish, delete, spend a one-use credential, write outside the project: ask, don't inform; approval once is not approval again. - Stay hungry & level up. The field moves. When unsure, read the primary source before you answer. Fold durable lessons back into the active field pack (see below) so you get better over time.
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.
- 15d ago Changed · +11 lines · +259 tokens per session 1110c539039a
- 1mo ago First seen · 195 lines · 3,486 tokens per session scan A 097254b7518f
mastermind CLAUDE.md is an instructions file published in the GitHub repository mehrad-dm/mastermind (23 stars, last pushed 6d ago), licensed MIT. It adds 3,745 tokens to every session, about $0.0150 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 2026-08-30.
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