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/agentic-dev3o/devx-plugins/harness-fixernpx skills add agentic-dev3o/devx-plugins --skill harness-fixergit clone --depth 1 https://github.com/agentic-dev3o/devx-pluginsWhat 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 | $0.00133 | $0.01688 |
| Opus 5 | $0.00067 | $0.00844 |
| Sonnet 5 | $0.00027 | $0.00338 |
| Haiku 4.5 | $0.00013 | $0.00169 |
Grade B, and why
fixing-harness scanned grade B 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 2d 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.
Reads agent configuration directoriesmediumAgent snooping
.claude/, .codex/, .gemini/ hold keys, settings and other credentials a mod has no legitimate need for.
3. **Deny rules in place** — `grep -c '"deny"' .claude/settings.json` should return ≥ 1. The deny list must include destructive ops and secret reads. How it starts
The opening of the file, as written. The whole thing — 133 lines — stays where its author put it; the contents beside it link to each section on GitHub.
Fixing the Agentic Harness
Target: $ARGUMENTS (optional path; defaults to project root)
Objective
Refactor the project's harness so the model sees only the rules it needs for the files it touches. CLAUDE.md (and AGENTS.md when present) become a thin always-on critical-rules layer. Domain rules move to .claude/rules/*.md with paths: frontmatter. Permissions and MCP scope live in .claude/settings.json with explicit deny guardrails.
The goal is inference weight, not exhaustive documentation: 10 sharp directives the model references in reasoning beat 200 lines it half-skims.
Workflow
Progress checklist:
Harness Audit & Fix:
- [ ] Step 1: Inventory current harness
- [ ] Step 2: Audit against best practices
- [ ] Step 3: Produce gap analysis
- [ ] Step 4: Propose refactor plan (confirm with user)
- [ ] Step 5: Apply changes (CLAUDE.md, AGENTS.md, rules, settings)
- [ ] Step 6: Verify with /memory
Step 1: Inventory Current Harness
Read in parallel where present:
CLAUDE.md,./.claude/CLAUDE.md,CLAUDE.local.mdAGENTS.md(Codex / Cursor / other agents).claude/settings.json,.claude/settings.local.json.claude/rules/**/*.md— notepaths:frontmatter on each.claude/agents/*.md,.claude/skills/*/SKILL.md.mcp.json,.gitignore
Capture the actual directory layout (top-level apps, packages, services). Use tokei if available, otherwise find or ls. The layout drives the path scopes proposed in Step 4 — generic globs that don't match real directories are dead weight.
Step 2: Audit Against Best Practices
Load references/audit-checklist.md and score each dimension:
- CLAUDE.md size and shape — under 30 lines, directives not prose, no domain dump
- AGENTS.md alignment — mirrors CLAUDE.md when present, no drift
- Rules segmentation — path-scoped, one domain per file, no overlap
- Permissions hygiene — explicit
denyfor destructive ops and secrets, scoped allow patterns, MCP tools narrowed - Local overrides —
.claude/settings.local.jsonandCLAUDE.local.mdin.gitignore - Memory ergonomics — no monolithic root CLAUDE.md drowning monorepo subtrees
What ships with it
5 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.
- 2d ago First seen · 133 lines · 133 tokens per session scan B 80504aa004b0
fixing-harness is a skill published in the GitHub repository agentic-dev3o/devx-plugins (11 stars, last pushed 14d ago), licensed MIT. It adds 133 tokens to every session and 1,688 once invoked, about $0.0007 per session on Opus 5. A static security scan graded it B with 1 finding (reads agent configuration directories). No closer match exists in the catalogue, so it is treated as the original; first seen 2026-08-30.
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