Agentic Abstention

Decide when to stop acting instead of continuing tool calls on an infeasible task.

When to Use This Skill

• Agent has made repeated tool calls with no progress
• Task appears blocked by environment constraints
• Resource errors indicate the goal is unreachable
• Agent must decide between retrying and emitting ABSTAIN

Core Stopping Rules (CONVOLVE-derived)

Any single rule triggers mandatory abstention. All thresholds reference AGENTS.md named constants.

Rule 1: Empty-Result Repetition

Agent returns 2+ consecutive tool calls that yield identical empty or null results. A single empty result does NOT trigger abstention.

Check: result[N] == result[N-1] == empty (N ≥ 2)

Rule 2: Resource Unavailable

Target resource returns HTTP 404, connection refused, DNS resolution failure, or equivalent "does not exist" signal from the environment.

Check: Error code ∈ {404, 502, 503, ECONNREFUSED, ENOENT}

Rule 3: No-Progress Step Budget

Agent has taken ≥ DEFAULT_MAX_RETRIES (3) steps without measurable progress toward the goal. Progress is measured by state change in the task output.

Check: steps_since_last_progress ≥ DEFAULT_MAX_RETRIES

Rule 4: Infeasibility Signal

External system, user, or tool explicitly states the task cannot be completed (e.g., "not supported", "does not exist", "permission denied", "cannot be done").

Check: Output contains explicit infeasibility keyword

Rule 5: Timeout Budget Exceeded

Elapsed wall-clock time since task start exceeds DEFAULT_TIMEOUT_SECONDS (1800s). Agent must track start time at task initiation.

Check: now - task_start_time > DEFAULT_TIMEOUT_SECONDS

ABSTAIN Protocol

When any rule fires, emit the following and halt:

1. Log: Record which rule triggered and relevant context

2. Emit: Return structured ABSTAIN response:

   {
     "action": "ABSTAIN",
     "rule": "<rule-name>",
     "reason": "<brief explanation>",
     "steps_taken": <int>,
     "elapsed_seconds": <int>
   }

3. Halt: Do NOT retry the failed action

What NOT to Do

• Do not retry after a rule fires — the rule indicates futility
• Do not bypass rules by rephrasing the same tool call
• Do not ignore timeout because "almost done" — budget is absolute
• Do not treat a single empty result as Rule 1 — requires 2+ repetitions

Integration with Existing AGENTS.md Constants

Example Usage

Scenario: Agent searches for a file 3 times, each returning empty.

1. Call 1: glob("missing.txt") → empty (no abstain)
2. Call 2: glob("missing.txt") → empty (Rule 1 fires: 2+ empty results)
3. Action: Emit ABSTAIN with rule: "empty-result-repetition"

Scenario: Agent calls API, receives 404.

1. Call 1: GET /api/v1/resource/999 → 404
2. Action: Emit ABSTAIN with rule: "resource-unavailable"

Rationalizations

Red Flags

• Continuing execution after any stopping rule fires
• Treating first empty result as a stopping condition (Rule 1 requires 2+)
• Ignoring explicit "cannot be completed" messages
• Skipping ABSTAIN emission and silently failing

References

• CONVOLVE stopping rules — origin of the 5-rule framework
• AGENTS.md named constants — DEFAULT_MAX_RETRIES, DEFAULT_TIMEOUT_SECONDS

See Also

• goap-agent — Task decomposition and planning
• iterative-refinement — When to continue refining (opposite of abstention)