# Writing SKILL.md for Discovery Part of superpowers:writing-skills: the SKILL.md template and how to name, describe and size a skill so agents find it and read it. ## SKILL.md Structure **Frontmatter (YAML):** - Two required fields: `name` and `description` (see [agentskills.io/specification](https://agentskills.io/specification) for all supported fields) - Max 1024 characters total - `name`: Use letters, numbers, and hyphens only (no parentheses, special chars) - `description`: Third-person, describes ONLY when to use (NOT what it does) - Start with "Use when..." to focus on triggering conditions - Include specific symptoms, situations, and contexts - **NEVER summarize the skill's process or workflow** (see Skill Discovery Optimization below for why) - Keep under 500 characters if possible ```markdown --- name: Skill-Name-With-Hyphens description: Use when [specific triggering conditions and symptoms] --- # Skill Name ## Overview What is this? Core principle in 1-2 sentences. ## When to Use [Small inline flowchart IF decision non-obvious] Bullet list with SYMPTOMS and use cases When NOT to use ## Core Pattern (for techniques/patterns) Before/after code comparison ## Quick Reference Table or bullets for scanning common operations ## Implementation Inline code for simple patterns Link to file for heavy reference or reusable tools ## Common Mistakes What goes wrong + fixes ## Real-World Impact (optional) Concrete results ``` ## Skill Discovery Optimization (SDO) **Critical for discovery:** Future agents need to FIND your skill ### 1. Rich Description Field **Purpose:** Your agent reads the description to decide which skills to load for a given task. Make it answer: "Should I read this skill right now?" **Format:** Start with "Use when..." to focus on triggering conditions **CRITICAL: Description = When to Use, NOT What the Skill Does** The description should ONLY describe triggering conditions. Do NOT summarize the skill's process or workflow in the description. **Why this matters:** Testing revealed that when a description summarizes the skill's workflow, an agent may follow the description instead of reading the full skill content. A description saying "code review between tasks" caused an agent to do ONE review, even though the skill's flowchart clearly showed TWO reviews (spec compliance then code quality). When the description was changed to just "Use when executing implementation plans with independent tasks" (no workflow summary), the agent correctly read the flowchart and followed the two-stage review process. **The trap:** Descriptions that summarize workflow create a shortcut agents will take. The skill body becomes documentation agents skip. ```yaml # ❌ BAD: Summarizes workflow - agents may follow this instead of reading skill description: Use when executing plans - dispatches subagent per task with code review between tasks # ❌ BAD: Too much process detail description: Use for TDD - write test first, watch it fail, write minimal code, refactor # ✅ GOOD: Just triggering conditions, no workflow summary description: Use when executing implementation plans with independent tasks in the current session # ✅ GOOD: Triggering conditions only description: Use when implementing any feature or bugfix, before writing implementation code ``` **Content:** - Use concrete triggers, symptoms, and situations that signal this skill applies - Describe the *problem* (race conditions, inconsistent behavior) not *language-specific symptoms* (setTimeout, sleep) - Keep triggers technology-agnostic unless the skill itself is technology-specific - If skill is technology-specific, make that explicit in the trigger - Write in third person (injected into system prompt) - **NEVER summarize the skill's process or workflow** ```yaml # ❌ BAD: Too abstract, vague, doesn't include when to use description: For async testing # ❌ BAD: First person description: I can help you with async tests when they're flaky # ❌ BAD: Mentions technology but skill isn't specific to it description: Use when tests use setTimeout/sleep and are flaky # ✅ GOOD: Starts with "Use when", describes problem, no workflow description: Use when tests have race conditions, timing dependencies, or pass/fail inconsistently # ✅ GOOD: Technology-specific skill with explicit trigger description: Use when using React Router and handling authentication redirects ``` ### 2. Keyword Coverage Use words an agent would search for: - Error messages: "Hook timed out", "ENOTEMPTY", "race condition" - Symptoms: "flaky", "hanging", "zombie", "pollution" - Synonyms: "timeout/hang/freeze", "cleanup/teardown/afterEach" - Tools: Actual commands, library names, file types ### 3. Descriptive Naming **Use active voice, verb-first:** - ✅ `creating-skills` not `skill-creation` - ✅ `condition-based-waiting` not `async-test-helpers` ### 4. Token Efficiency (Critical) **Problem:** getting-started and frequently-referenced skills load into EVERY conversation. Every token counts. **Target word counts:** - getting-started workflows: <150 words each - Frequently-loaded skills: <200 words total - Other skills: <500 words (still be concise) **Techniques:** **Move details to tool help:** ```bash # ❌ BAD: Document all flags in SKILL.md search-conversations supports --text, --both, --after DATE, --before DATE, --limit N # ✅ GOOD: Reference --help search-conversations supports multiple modes and filters. Run --help for details. ``` **Use cross-references:** ```markdown # ❌ BAD: Repeat workflow details When searching, dispatch subagent with template... [20 lines of repeated instructions] # ✅ GOOD: Reference other skill Always use subagents (50-100x context savings). REQUIRED: Use [other-skill-name] for workflow. ``` **Compress examples:** ```markdown # ❌ BAD: Verbose example (42 words) your human partner: "How did we handle authentication errors in React Router before?" You: I'll search past conversations for React Router authentication patterns. [Dispatch subagent with search query: "React Router authentication error handling 401"] # ✅ GOOD: Minimal example (20 words) Partner: "How did we handle auth errors in React Router?" You: Searching... [Dispatch subagent → synthesis] ``` **Eliminate redundancy:** - Don't repeat what's in cross-referenced skills - Don't explain what's obvious from command - Don't include multiple examples of same pattern **Verification:** ```bash wc -w skills/path/SKILL.md # getting-started workflows: aim for <150 each # Other frequently-loaded: aim for <200 total ``` **Name by what you DO or core insight:** - ✅ `condition-based-waiting` > `async-test-helpers` - ✅ `using-skills` not `skill-usage` - ✅ `flatten-with-flags` > `data-structure-refactoring` - ✅ `root-cause-tracing` > `debugging-techniques` **Gerunds (-ing) work well for processes:** - `creating-skills`, `testing-skills`, `debugging-with-logs` - Active, describes the action you're taking ### 5. Cross-Referencing Other Skills **When writing documentation that references other skills:** Use skill name only, with explicit requirement markers: - ✅ Good: `**REQUIRED SUB-SKILL:** Use superpowers:test-driven-development` - ✅ Good: `**REQUIRED BACKGROUND:** You MUST understand superpowers:systematic-debugging` - ❌ Bad: `See skills/testing/test-driven-development` (unclear if required) - ❌ Bad: `@skills/testing/test-driven-development/SKILL.md` (force-loads, burns context) **Why no @ links:** `@` syntax force-loads files immediately, consuming 200k+ context before you need them.