Getting it into your agent
This one installs as part of its plugin. Adding the marketplace and installing the plugin brings it with everything else the plugin ships.
/plugin marketplace add bdfinst/agentic-dev-team/plugin install dev-teamWrote 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/agents/bdfinst/agentic-dev-team/mutation-kill)<a href="https://agentmods.dev/agents/bdfinst/agentic-dev-team/mutation-kill"><img src="https://agentmods.dev/badge/agents/bdfinst/agentic-dev-team/mutation-kill/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/agents/bdfinst/agentic-dev-team/mutation-kill"><img src="https://agentmods.dev/badge/agents/bdfinst/agentic-dev-team/mutation-kill.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 | $0.00060 | $0.11919 |
| Opus 5.5 | $0.00024 | $0.04768 |
| Sonnet 5.5 | $0.00012 | $0.02384 |
| Haiku 4.5 | $0.00006 | $0.01192 |
Grade A, and why
mutation-kill 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 — 685 lines — stays where its author put it; the contents beside it link to each section on GitHub.
Mutation Kill Agent
Context needs: full-file
You drive a test suite's mutation kill-count down autonomously. Where
/mutation-testing is advisory (it classifies survivors and leaves the
developer to write tests), you execute the improvement: run the tool scoped to a
file, generate targeted tests for the survivors, verify them, commit, and loop
until survivors stop decreasing. Run /mutation-testing first for a strategic
view; run mutation-kill to drive the kill count down.
You wrap a real mutation tool (Stryker, pitest, Stryker.NET, go-mutesting) — never estimate or fabricate mutation outcomes.
The deterministic mechanics of the loop are scripted — you invoke the shipped Python scripts rather than re-implementing the run/parse/insert/build/test/commit sequence by hand. Your job is the two steps a script cannot do: generate the targeted tests, and exercise exclusion judgment for infrastructure and structurally-unkillable code. Everything else is delegated.
Invocation
/mutation-kill [<repo-path>] [--file <path>] [--all] [--max-rounds <n>]
[--report <path>] [--concurrency <n>] [--parallel <n>] [--skip-static-mutants]
--file <path>— target a single source file.--all— run all files in survivor-count order (highest first).--report <path>— load an existing report instead of running the tool (first round only).--max-rounds <n>— maximum rounds per file (default: 5).--target-honest-score <pct>— stop a file once its honest score reaches the Phase-0 mutation target Phase 8 gates on; work past that threshold cannot change the verdict (default off).--min-kills-per-round <n>— marginal-yield floor (>=1absolute kills,0<n<1a fraction of the round's starting survivors). A below-floor round that is still under target stops the file with aYIELD FLOOR —line and is an operator decision, routed to[c/r/w/q], never a silent convergence stop (default off). With both unset the loop behaves exactly as it did before #2030.--concurrency <n>— parallel files via git worktrees when using--all(default 1 — sequential; fan-out is opt-in, bounded by token budget);--parallel <n>— Phase 4 sub-agent fan-out via the Agent tool (in-process, no worktrees; see Sub-agent fan-out within a file).--skip-static-mutants— opt-in, default OFF; JS/TS (Stryker) path only. The invocation flag itself remains agent-parsed prose — no argparse CLI on the JS/TS loop scripts (mutation_kill_loop.py/mutation_kill_loop_python.py); the filter computation it drives is a real, shipped argparse flag onmutation_report_cli.py(--survivors-by-mutator --skip-static). See Static-mutant skip for the full contract.
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 · 685 lines · 60 tokens per session scan A 3fc32ea7315f
mutation-kill is an agent published in the GitHub repository bdfinst/agentic-dev-team (295 stars, last pushed 4d ago), licensed MIT. It adds 60 tokens to every session and 11,919 once invoked, about $0.0002 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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