Skill Construction

skill-construction

Builds a Claude Code skill (the SKILL.md file plus any resource files and the evaluation rubric) from a structured set of extracted components and a synthesis verdict. The penultimate step in the skill-creator workflow.

The skill is invoked by the calling agent (typically the skill-creator agent) once synthesis-application has produced a GO or GO_WITH_GAPS verdict on the extracted components. NO_GO sends the agent back upstream.

Workflow

- [ ] Step 1: Assess complexity level (1-3) from extracted content volume
- [ ] Step 2: Plan resource files (or decide SKILL.md alone is enough)
- [ ] Step 3: Draft SKILL.md frontmatter (name, description, triggers)
- [ ] Step 4: Draft SKILL.md body (workflow checklist, key patterns, guardrails)
- [ ] Step 5: Draft each resource file (focused topic, < 500 lines, WHY/WHAT structure)
- [ ] Step 6: Construct an evaluation rubric (10 criteria, 1-5 scale)
- [ ] Step 7: Output the constructed skill files

Inputs

• extracted_components: structured terms / propositions / arguments / solutions from component-extraction
• synthesis_output: the GO / GO_WITH_GAPS verdict from synthesis-application plus its gap-fill recommendations
• target_dir: where the skill should be written (typically skills/{skill-name}/)
• purpose_context: e.g., skill_extraction_from_methodology (the standard case)

Complexity levels

Match structure to content volume. Don't over-engineer; don't under-engineer.

Decide based on:

• Total workflow steps the methodology has
• Major decision points (each typically warrants a section)
• Number of distinct concepts that need explanation
• Examples needed (more examples → more lines → likely Level 2 or 3)

SKILL.md structure (always required)

YAML frontmatter:

• name: lowercase-hyphens, ≤64 chars, no XML, no reserved words ("anthropic", "claude")
• description: third-person, both what the skill does AND when to use it, including trigger keywords. ≤1024 chars. This is the discovery surface — Claude uses it to decide whether to invoke the skill.

Body sections (typical order):

• # {Skill Name} — title + one-paragraph framing
• ## Workflow — checklist the calling agent can copy
• ## {Domain-specific sections} — patterns, decision logic, key concepts
• ## Common patterns — 2-4 named patterns with usage context
• ## Guardrails — must-nots and anti-patterns
• ## Related — pointers to adjacent skills (one level deep only)

Resource file structure (Level 2 and 3)

Each resource file:

• Focused on one cohesive topic (don't sprawl)
• < 500 lines
• Cross-referenced from SKILL.md as a one-level-deep link
• Follows a ## Why X then ## What to do structure (the WHY activates context; the WHAT gives concrete instructions)

Two grouping approaches:

• By workflow step (best for complex skills) — one resource file per major step, named for the step
• By topic (best for moderate skills) — key-concepts.md, decision-framework.md, examples.md

Evaluation rubric

Always include resources/evaluators/rubric_{skill_name}.json. 10 criteria, each scored 1-5. Common criteria:

1. Description specificity (third person, what + when, triggers)
2. Workflow completeness (all major steps captured)
3. Pattern coverage (common cases addressed)
4. Guardrail clarity (must-nots are concrete)
5. Example quality (examples are concrete, not abstract)
6. Resource organization (files focused, one-level-deep links)
7. Token efficiency (no over-explanation; assumes Claude is smart)
8. Consistency (terminology stable; format matches across sections)
9. Triggers explicit (key phrases listed in description)
10. Tested (at least one real-world test case considered)

Target average ≥ 3.5 before shipping.

Output structure

## Skill Construction Output

### Complexity assessment
Level: {1 | 2 | 3}
Rationale: {1-2 sentences}
Structure: {file list}

### Files created
- {target_dir}/SKILL.md ({line count} lines)
- {target_dir}/resources/{file}.md ({line count} lines) — {topic}
- ...
- {target_dir}/resources/evaluators/rubric_{name}.json (10 criteria)

### Self-evaluation against the rubric
- Average score: {X / 5}
- Below-3 criteria: {list}
- Recommended next-pass focus: {1-2 specific improvements}

### Gaps from upstream synthesis-application
{If the synthesis verdict was GO_WITH_GAPS, restate the gap list and how the construction addressed each (filled / deferred / surfaced as a TODO in the SKILL).}

Anchoring against authoring best practices

Conform to Anthropic's agent skills authoring best practices:

• Concise is key. Only add context Claude doesn't already have. Challenge each piece: "does Claude need this explanation?"
• Set appropriate degrees of freedom. High freedom (text instructions) for judgment calls; low freedom (specific scripts) for fragile procedures.
• Keep references one level deep. SKILL.md links directly to resource files; resources don't link to other resources.
• Workflow checklists for complex tasks. Calling agent can copy and check off as it progresses.
• Feedback loops. Validator → fix errors → repeat.
• Avoid Windows-style paths. Forward slashes always.
• Avoid offering too many options. One default with an escape hatch beats five alternatives.
• MCP tools use fully qualified names. ServerName:tool_name.

Common patterns

Pattern A — From a methodology document (the standard skill-creation case)

The extracted components come from a methodology guide or framework doc. Workflow steps in SKILL.md mirror the methodology's steps. Resources cover decision logic, examples, and templates.

Pattern B — From a research paper

Less common but valid. The extraction yields propositions and arguments more than steps. SKILL.md becomes a "how to apply this paper's framework to a downstream task" guide. Resources cover the paper's framework and worked examples.

Pattern C — Refactoring an existing skill

The "extracted components" come from an existing skill that's grown too large or has overlap with another. The construction step writes a leaner version, deferring resources to focused files.

Guardrails

1. Don't construct without a GO verdict. If synthesis-application returned NO_GO, return upstream — building a skill from incomplete components is wasted work.
2. Don't exceed 500 lines in SKILL.md body. Push depth into resource files.
3. Don't skip the rubric. Self-evaluation gates ship-readiness; without a rubric there's no objective standard.
4. Don't over-engineer. A 3-step methodology is Level 1 — don't build it as Level 3 because resources feel "more professional."
5. Don't use Anthropic's reserved words in name. "claude", "anthropic" — silently breaks discovery.
6. Don't claim test coverage you don't have. The rubric's "Tested" criterion is a real check; mark it 1 if no test scenario was considered.

Related

• component-extraction — produces the input this skill consumes.
• synthesis-application — runs immediately before this skill; its GO / GO_WITH_GAPS / NO_GO verdict gates this skill's invocation.
• evaluation-rubrics — the rubric construction in this skill's Step 6 mirrors the rubric design patterns there.
• The skill-creator skill at skills/skill-creator/SKILL.md invokes this skill as its Step 5.