Acceptance Criteria: Define

Step 0: Check for Context

If no request or task description was provided as context (the skill was invoked with no arguments and nothing in the conversation describes a feature, task, or plan to evaluate):

• Output: "This skill needs a request or task description as context. Please describe the feature or task you want acceptance criteria for, or point me to a plan file."
• STOP — do not continue.

Step 1: Identify the Plan File (if any)

Check whether the context references an implementation plan file:

• Look for a file path ending in .md mentioned in the request or conversation (e.g., .agents/plans/feature-name.md)
• Look for any .agents/plans/*.md file that matches the feature being discussed

If a plan file is identified:

• Read the entire plan file now
• Scan for an existing ## ACCEPTANCE CRITERIA or ## Acceptance Criteria section
• If found, extract and note the existing criteria — these are your starting point
• Also scan the ## TESTING STRATEGY, ## VALIDATION COMMANDS, and ## Feature Description sections to understand the full scope

If no plan file:

• Proceed with the request description from conversation context only

Step 2: Derive Acceptance Criteria

Based on the context (plan file, feature description, or request in conversation), derive the acceptance criteria.

Think through each of these dimensions and produce criteria for whichever apply:

Functional Correctness

• What must the feature actually do? (the happy paths)
• What inputs/outputs define success?
• What specific behaviors are required vs. optional?

Error Handling & Edge Cases

• What happens on bad input, missing data, or failures?
• What state should the system be in after an error?

Integration & End-to-End Flow

• What connected systems must work together for the feature to be considered complete?
• What does "it works" look like from the user's perspective end-to-end?

Validation & Test Coverage

• Which test levels are required: unit, integration, E2E?
• What automated validation commands should pass before accepting the work?
• Are there manual steps required for final verification?

Non-Functional Requirements

• Performance: any latency, throughput, or load requirements?
• Security: any auth, data handling, or secret management requirements?
• Observability: logging, error reporting, tracing requirements?

Not In Scope

• Explicitly list what is NOT expected — this prevents scope creep during review

Format each criterion as a concrete, testable statement, not a vague goal.

Good: "The /mcp/mcp endpoint returns HTTP 200 with a valid MCP tools list when the server is running" Bad: "The server should work correctly"

Step 3: Present Criteria to User

Output your derived criteria in a clear, readable list. Use this format:

## Proposed Acceptance Criteria

### Functional
- [ ] <criterion>
- [ ] <criterion>

### Error Handling
- [ ] <criterion>

### Integration / E2E
- [ ] <criterion>

### Validation
- [ ] <criterion> — verified by: `<command or test>`

### Out of Scope
- <item> — not required for this task

Then use AskUserQuestion to ask the user:

Question: "Do these acceptance criteria look right, or would you like to define them yourself?" Options:

1. "Looks good — use these" — proceed with the proposed criteria as-is
2. "I want to add/change something" — user will provide modifications in free text
3. "Let me define them myself" — skip the proposed criteria entirely and wait for the user to write their own

Step 4: Finalize the Criteria

If user selected option 1 (use as-is):

• Use the proposed criteria verbatim

If user selected option 2 (add/change):

• Read the user's modifications from their reply
• Merge them with the proposed criteria:
  • Additions: append to the relevant section
  • Changes: replace the relevant criteria
  • Removals: remove any criteria the user rejected
• Output the final merged list to the user before writing

If user selected option 3 (define themselves):

• Wait for the user to provide the criteria
• Do not invent or add criteria they did not provide
• Use exactly what the user wrote

Step 5: Write the Criteria

Case A: A plan file was identified

Rewrite the ## ACCEPTANCE CRITERIA section at the bottom of the plan file.

• If the section already exists: replace its entire contents with the final criteria
• If the section does not exist: append it before ## COMPLETION CHECKLIST if that section exists, otherwise at the very end of the file
• Use the exact heading ## ACCEPTANCE CRITERIA
• Format each criterion as a - [ ] checkbox item
• Include the "Out of Scope" list as a plain bullet list (not checkboxes) under a ### Out of Scope subsection

Use the Edit tool to make this change — read the file first if you have not already.

After writing, output: "Acceptance criteria written to <plan-file-path>."

Case B: No plan file — write to acceptance_criteria.md

Check if acceptance_criteria.md exists in .agents/ (preferred) or the project root.

If the file does NOT exist:

Create .agents/acceptance_criteria.md with this structure:

# Acceptance Criteria

---

## <short title derived from the request> — <date>

### Context
<2–4 sentence summary of the request or feature this criteria applies to>

### Criteria

#### Functional
- [ ] <criterion>

#### Error Handling
- [ ] <criterion>

#### Integration / E2E
- [ ] <criterion>

#### Validation
- [ ] <criterion> — verified by: `<command>`

#### Out of Scope
- <item>

If the file ALREADY EXISTS:

Read the file first. Append a new section after the last existing section:

---

## <short title derived from the request> — <date>

### Context
<summary>

### Criteria
...

Do NOT modify any existing sections.

After writing, output: "Acceptance criteria written to .agents/acceptance_criteria.md."

Step 6: Summary

Output a brief confirmation:

Acceptance criteria saved.

File: <path>
Criteria: <N> items
Next step: Run /execute <plan-file> to implement, or share the criteria with the agent executing this work.

If this skill was invoked as part of a planning or execution flow, return control to the calling skill now.