eval-author

name	eval-author
description	Generate scenario stubs for /eval against a target agent or skill. Reads recent successful invocations from session transcripts and proposes 5+ scenarios covering happy path, edge cases, and negative cases. Triggers on /eval-author, "author scenarios for X", "create eval scenarios", "generate test cases for the X agent".
when_to_use	Before first /eval run on a target. After deploying a new agent or skill. When existing scenarios are stale.
allowed-tools	Read, Write, Glob, Grep, Bash
arguments	["target"]

/eval-author — Generate eval scenario stubs

/eval-author <target> produces 5+ starter scenario .md files at ~/.claude/evals/scenarios/<target>/.

What you do

1. Resolve target

• Skill (~/.claude/skills/<name>/) → scenarios test that the skill triggers correctly + produces useful output
• Agent (~/.claude/agents/<name>.md) → scenarios test the agent's protocol (happy + edge + adversarial)
• Rule (~/.claude/rules/<name>.md or CLAUDE.md) → scenarios test that Claude follows the rule

2. Read the target

Open the target's .md file. Extract:

• Description (what should trigger it)
• Protocol (what it does)
• Anti-patterns (what it should NOT do)
• Output format (what to validate)

3. Mine recent successful invocations

Find the last ~10 sessions where this target was used:

grep -l 'subagent_type":"<target>"' ~/.claude/projects/*/*.jsonl | head -10
# or for skills
grep -l '"skill":"<target>"' ~/.claude/projects/*/*.jsonl | head -10

For each, extract the user prompt that triggered it and a sketch of the expected output.

4. Generate scenarios

Author scenarios covering:

• 2 happy paths — typical successful invocation
• 1 negative trigger — a prompt that should NOT activate this target (test for false-positive triggering)
• 1 ambiguous case — adversarial; expected result depends on judgment, document the expected behavior
• 1 edge case — failure mode the protocol handles (or should)

5. Write each scenario

Format (frontmatter + optional body):

---
name: <slug>
description: <one-line>
prompt: "<single-line user prompt>"
expects_skills:
  - <skill-name>     # if this scenario should activate a skill
expects_tools:
  - Bash             # tools that must appear
expects_agents:
  - <agent-name>     # subagent_types that should be spawned
rubric:
  - criterion: "<testable behavior>"
    weight: <1-3>
  - ...
---

## Why this scenario
<reason this case is worth testing>

## What good looks like
- <bullet>

## What bad looks like
- <bullet>

6. Verify

After writing all 5, run:

ls ~/.claude/evals/scenarios/<target>/

Show the user. They can run /eval <target> to execute them.

Bootstrapping when no past invocations exist

If grep finds no prior invocations of the target (new agent/skill), author scenarios from the protocol description alone:

• Read each protocol step. Each has implicit success criteria → that's a rubric criterion.
• Each anti-pattern is a negative case to test.
• Description is the trigger phrase to validate.

Anti-patterns

• Writing scenarios with vague rubric criteria ("works well")
• Copy-pasting the same prompt across scenarios (variety matters)
• Forgetting the negative trigger (false positives are as bad as false negatives)
• Authoring 20 scenarios — quality over quantity. 5 sharp scenarios beat 20 mush.
• Using prompts that wouldn't realistically be typed by a user