define-done

define-done is a skill for Claude Code, Codex from haabe/mycelium. It costs 52 tokens per session (3,907 once invoked), scanned A, original, MIT.

A skill for setting a clear, measurable Definition of Done: the observable change in people’s behaviour that shows a project has created value.

In plain words
What is it for?
Use it when starting a project goal, called a diamond, or when an existing goal lacks a specific outcome to measure.
Why use it?
It prevents teams from treating a shipped feature or completed checklist as proof that the work succeeded.

Skill for Claude CodeCodex

Installs and runs on its own, but its text points at files inside its plugin — anything it tells you to read at a ${CLAUDE_PLUGIN_ROOT} path is only there once the plugin is installed. Installing the plugin gets both.

Part of the mycelium plugin — 54 skills, 6 hooks shipped together

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.

agentmods
npx agentmods add skills/haabe/mycelium/define-done
Any agent
npx skills add haabe/mycelium --skill define-done
Clone the repo
git clone --depth 1 https://github.com/haabe/mycelium

Made for: Claude Code, Codex.

Or install mycelium, the plugin that ships this one along with the rest of its 54 skills, 6 hooks.

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 define-done

README.md
[![agentmods](https://agentmods.dev/badge/skills/haabe/mycelium/define-done.svg)](https://agentmods.dev/skills/haabe/mycelium/define-done)
Your own site
<a href="https://agentmods.dev/skills/haabe/mycelium/define-done"><img src="https://agentmods.dev/badge/skills/haabe/mycelium/define-done.svg" alt="Measured on agentmods" height="20"></a>
Per session 52 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 3,907 The whole file, excluding the scripts and references it only reads on demand.
Security scan A 0 findings. Scan, not verified.
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 $0.00052 $0.03907
Opus 5 $0.00026 $0.01954
Sonnet 5 $0.00010 $0.00781
Haiku 4.5 $0.00005 $0.00391

Measured 4d ago against content hash 4cd9cc841ff1, method: parsed. Prices are Anthropic first-party input rates as of 2026-08-30, from the pricing page.

Security

Grade A, and why

define-done 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 4d 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.

plugins/mycelium/skills/define-done/SKILL.md · 170 lines

How it starts

The opening of the file, as written. The whole thing — 170 lines — stays where its author put it; the contents beside it link to each section on GitHub.

Define Done

Pin an explicit, outcome-based Definition of Done for a diamond. "Done" is a change in human behaviour that creates value (Seiden), not "the feature shipped" — you're done when it ships and has the intended impact (Amplitude). The diamond's implicit done defaults to the harshest, least-controllable bar ("a user shipped a product"), which is both wrong for validating purpose and a demotivation engine. This skill makes the bar explicit, measurable, and pre-committed.

This is distinct from /mycelium:definition-of-done (the per-feature agile quality checklist run at Deliver→Complete). This skill sets the outcome bar a whole diamond is judged against; that one verifies a feature meets quality criteria. Both can apply.

When to use

  • At diamond birth/mycelium:interview (L0) and child-diamond spawn (/mycelium:diamond-progress) call this before a diamond is "live."
  • Retrofit — when /mycelium:canvas-health, /mycelium:diamond-assess, or the SessionStart nudge flags a diamond with no definition_of_done.
  • Never silent-fill. The question is what produces a real bar ("fits, not ships"); a back-filled field is theatre.

Preflight: Read target file before any Write/Edit

Hard rule. The definition_of_done field lives on the diamond in .claude/diamonds/active.yml. Before Write/Edit on it, use the Read tool on that file this session (cat/head/grep via Bash do NOT satisfy Claude Code's check). Edit with limit:1 suffices for a partial update; full Read before a Write. See CLAUDE.md Canvas writes — Read before Write.

The sequence (Socratic, problem-first)

Ask these in order. The teaching is in the sequencing (problem → signal → maybe-number → kill) and the good/bad contrast — not a help doc. Reject build-lists at step 1; that is the whole point.

1. "When this is done, what's different — and for WHOM?"outcome + whose behaviour. Lead with the problem and the person, never the deliverable (Cagan: "most measurement problems are clarity problems").

  • "the onboarding flow ships." (a build-list — reject it)
  • "non-fluent users get through the brief without hitting the vocabulary wall."

Read the full file on GitHub · 170 lines

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. 4d ago First seen · 170 lines · 52 tokens per session scan A 4cd9cc841ff1

Subscribe to this mod's changes

define-done is a skill published in the GitHub repository haabe/mycelium (45 stars, last pushed today), licensed MIT. It adds 52 tokens to every session and 3,907 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 2026-08-30.

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