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 agentmods add skills/stefaniuk/loadout/mutation-testingnpx skills add stefaniuk/loadout --skill mutation-testinggit clone --depth 1 https://github.com/stefaniuk/loadoutWhat 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 | $0.00053 | $0.00690 |
| Opus 5 | $0.00026 | $0.00345 |
| Sonnet 5 | $0.00011 | $0.00138 |
| Haiku 4.5 | $0.00005 | $0.00069 |
Grade A, and why
mutation-testing 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 yesterday.
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.
This is a copy
95% identical to mutation-testing — 5 lines differ, which has more behind it and is treated as the original. This page carries a canonical link to it rather than competing with it.
How it starts
The opening of the file, as written. The whole thing — 70 lines — stays where its author put it; the contents beside it link to each section on GitHub.
Mutation Testing — Campaign Configuration (mewt/muton)
Note: muton and mewt share identical interfaces but target different languages — mewt for general-purpose languages (Rust, Solidity, Go, TypeScript, JavaScript), muton for TON smart contracts (Tact, Tolk, FunC). All examples use
mewtcommands, but they work exactly the same withmuton. File names change accordingly:mewt.toml→muton.toml,mewt.sqlite→muton.sqlite.
When to Use
Use this skill when the user:
- Mentions "mewt", "muton", or "mutation testing"
- Needs to configure or optimize a mutation testing campaign
- Wants to run
mewt runand needs help getting set up first
When NOT to Use
Do not use this skill when the user:
- Wants to analyze or report on completed campaign results
- Asks about tests or coverage without mentioning mutation testing
Quick Start
Load workflows/configuration.md — a 5-phase guide from mewt init to a validated, ready-to-run campaign.
General question or unfamiliar command?
Run mewt --help or mewt <subcommand> --help, then assist.
Reference Index
| File | Content |
|---|---|
| workflows/configuration.md | 5-phase guide: init, scope, optimize, validate, run |
| references/optimization-strategies.md | Per-file targeting, two-phase campaigns, mutation type filtering |
Essential Commands
# Initialize and mutate
mewt init # Create mewt.toml and mewt.sqlite
mewt mutate [paths] # Generate mutants without running tests
mewt run [paths] # Run the full campaign
# Inspect configuration and scope
mewt print config # View effective configuration
mewt print targets # Table of all targeted files
mewt print mutations --language [lang] # Available mutation types
mewt status # Mutant count and per-file breakdown
# Investigate specific mutants
mewt print mutants --target [path] # All mutants for a file
mewt print mutants --severity high # Filter by severity
mewt print mutant --id [id] # View mutated code diff
mewt test --ids [ids] # Re-test specific mutants
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.
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.
- yesterday First seen · 70 lines · 53 tokens per session scan A c36bf0cc61f5
mutation-testing is a skill published in the GitHub repository stefaniuk/loadout (1 stars, last pushed 4d ago), licensed MIT. It adds 53 tokens to every session and 690 once invoked, about $0.0003 per session on Opus 5. A static security scan graded it A with 0 findings. It is 95% identical to mutation-testing, differing in 5 lines, and is treated as a copy.
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