harness

harness is a skill for Claude Code from vasuag09/harness-claude. It costs 55 tokens per session (556 once invoked), scanned A, original, MIT.

A complete software-development workflow that coordinates planning, implementation, verification, and optional maintenance. It pauses between these stages for your approval.

In plain words
What is it for?
Use it for a complete feature or change when you want requirements and design checked, code implemented, results verified, and cleanup offered afterward.
Why use it?
It gives a structured path from a one-line idea to work that is ready to merge, while making the results of each stage visible before the next begins.

Skill for Claude Code

Written for Claude Code: shipped in a Claude Code plugin. Also seen: mentions subagents.

Part of the harness-claude plugin — 32 skills, 8 agents, 6 hooks, 3 MCP servers shipped together

Good fit Use it for a complete feature or change when you want requirements and design checked, code implemented, results verified, and cleanup offered afterward.

Compare 6 skills from other repositories ↓
Install with agentmods
npx agentmods add skills/vasuag09/harness-claude/harness
Install

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.

Any agent
npx skills add vasuag09/harness-claude --skill harness
Clone the repo
git clone --depth 1 https://github.com/vasuag09/harness-claude

Made for: Claude Code.

Or install harness-claude, the plugin that ships this one along with the rest of its 32 skills, 8 agents, 6 hooks, 3 MCP servers.

Wrote 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.

agentmods badge for harness

README.md
[![agentmods](https://agentmods.dev/badge/skills/vasuag09/harness-claude/harness/github.svg)](https://agentmods.dev/skills/vasuag09/harness-claude/harness)
Your own site
<a href="https://agentmods.dev/skills/vasuag09/harness-claude/harness"><img src="https://agentmods.dev/badge/skills/vasuag09/harness-claude/harness/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.

agentmods 80×15 button for harness

Your own site · 80×15
<a href="https://agentmods.dev/skills/vasuag09/harness-claude/harness"><img src="https://agentmods.dev/badge/skills/vasuag09/harness-claude/harness.svg" alt="Reviewed on agentmods" width="80" height="20"></a>
Per session 55 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 556 The whole file, excluding the scripts and references it only reads on demand.
Security scan A 0 findings. A grade says what 26 rules found in the file — not that it is safe.
Origin original No closer match found in the catalogue.
Token cost

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.

ModelPer sessionOnce invoked
Fable 5.1 $0.00055 $0.00556
Opus 5 $0.00028 $0.00278
Sonnet 5 $0.00011 $0.00111
Haiku 4.5 $0.00006 $0.00056

Measured 9d ago against content hash f256055f654f, method: parsed. Prices are Anthropic first-party input rates as of 2026-09-09, from the pricing page.

Security

Grade A, and why

harness 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 9d 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.

skills/harness/SKILL.md · 43 lines

What it actually says

/harness — the full pipeline

The top-level orchestrator. It walks all four phases by invoking the phase orchestrators in order, pausing at every phase boundary for your go-ahead. It is a convenience wrapper — it adds checkpoints and a running summary, nothing the phase skills don't already do.

Flow

/harness-claude:harness-plan ──▶ [checkpoint] ──▶ /harness-claude:harness-implement ──▶ [checkpoint]
   ──▶ /harness-claude:harness-verify ──▶ [checkpoint] ──▶ /harness-claude:harness-maintain (optional)
  1. Plan — run /harness-claude:harness-plan. At its HALTs, get the user's answers/approvals. → CHECKPOINT: show the approved spec + plan (+ ADR). Wait for "go" before coding.

  2. Implement — run /harness-claude:harness-implement against the approved plan. → CHECKPOINT: report what was built and test status. Wait for "go" before verify.

  3. Verify — run /harness-claude:harness-verify. Halt on Critical/High; stop at the git boundary. → CHECKPOINT: show review/security verdicts, coverage, observed-working evidence.

  4. Maintainoffer /harness-claude:harness-maintain. Run it only if the user wants cleanup now.

Rules

  • Honor every HALT and CHECKPOINT — this is a guided pipeline, not an autonomous run.
  • Delegate heavy work to subagents; /harness-claude:save-session at each checkpoint so a long feature survives compaction or a new session.
  • Never commit or push without an explicit user ask — branch creation happens automatically at first write in the Implement phase (rules/git.md). /harness-claude:harness-verify ends at "ready to commit/PR."
  • For a small change, a single phase orchestrator (or atomic skill) is lighter — /harness-claude:harness is for full features.

Output

A phase-by-phase rollup ending in "merge-ready (awaiting your git go-ahead)."

Changes

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.

  1. 9d ago First seen · 43 lines · 55 tokens per session scan A f256055f654f

Subscribe to this mod's changes

harness is a skill published in the GitHub repository vasuag09/harness-claude (2 stars, last pushed 2mo ago), licensed MIT. It adds 55 tokens to every session and 556 once invoked, about $0.0003 per session on Opus 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 2026-08-31.

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