Claude Opus 5.5 (effort default (no --effort flag) · thinking on) on Write a blameless postmortem from a timeline + chat export (automated rubric)

AClaude Opus 5.5default · thinking on · Claude Code 2.1.299 (headless -p) · cloud · 2026-10-16 · by @bobsiopener

Trust 80%Fully autonomoussuccess · first tryCompare

Estimated cost: $0.21
Wall time: 42s
Human step-ins: 0
Outcome: Pass

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Rescored on 2026-10-28. Previous score: 72.5 / 100, outcome: success. See the previous run.

Exact prompt

# Task: write a blameless postmortem Using ONLY `inputs/timeline.csv` and `inputs/chat_export.txt`, write `postmortem.md` (400–700 words) with these exact H2 sections in this order: `## Summary`, `## Impact`, `## Timeline`, `## Root cause`, `## Detection`, `## What went well`, `## What went wrong`, `## Action items`. Requirements: blameless (no individual is blamed; do not name the person who left), state durations and numbers exactly as in the sources (compute duration yourself), action items as a list each with an owner ROLE (not a person's name) and a due-date placeholder `TBD`. Do not invent facts or numbers. No network.

Write a blameless postmortem from an incident timeline and a chat export, with eight required sections in a fixed order and 400-700 words. Numbers and durations must match the sources, the employee who left must not be named, and action items need role owners. The scorer also rejects any number that does not appear in the sources. Original benchmark task written for usecaserank.com (not based on a specific public post). Headless, offline run on a reproducible fixture. Each run's notes say how its cost was measured (estimates are marked).

Success criteria: 1. Exactly these H2 sections in this order: Summary, Impact, Timeline, Root cause, Detection, What went well, What went wrong, Action items. 2. 400–700 words. 3. States the correct incident duration (as hours+minutes or total minutes), and both the start and end times from the sources. 4. States the exact failed-payment count and affected-customer count from the sources. 5. Root cause section mentions an expired certificate; Detection section mentions customers/tweets/support and the alert/threshold problem. 6. Blameless: the departed employee is not named; no 'fault', 'blame', 'careless', 'negligent' wording. 7. At least 4 action-item bullets, every one containing 'TBD', and no person names in the Action items section. 8. No invented numbers: every number in the text must appear in the source files (a few small integers are whitelisted).

Setup notes: Use Case Scout batch 3 case c10-postmortem-rubric (offline fixture). Prepared with the case's setup script; hidden key/tests kept outside the agent's work dir. Prompt = TASK.md verbatim. Scored automatically with the scout's scorer. Tools: Read/Write/Edit/Glob/Grep/Bash, web disabled. Single run, no retries. Rescored 2026-10-16 with Scout's fixed scorer. The original score was 12/14 checks (fail), and the model's output is unchanged. Rubric change 2026-10-17: one check was moved to an unscored flag. Claude Code's own reported cost for claude-opus-5.5: $0.210619. Score: 13/13 checks. Cost is an ESTIMATE: measured tokens x the site's list-price table (Claude Pro subscription, nothing billed); input tokens include cache reads and writes. Single run. Full scorer detail is kept in our audit records.

Estimated cost List-price estimate; not actually billed.

Metrics

Estimated cost: $0.21
Wall time: 42s
Human step-ins: 0
Turns: 6

Model usage
Model	Input tok	Output tok	Cost
AClaude Opus 5.5anthropic/claude-opus-5.5effort default (no --effort flag) · thinking on	126,773	4,453	$0.21

Reproduce this run

Use the use case prompt on the use case page.
Same setup: Claude Opus 5.5 (anthropic/claude-opus-5.5, effort default (no --effort flag) · thinking on) via Claude Code 2.1.299 (headless -p), cloud.
It counts as a success only if it meets every success criterion: 1. Exactly these H2 sections in this order: Summary, Impact, Timeline, Root cause, Detection, What went well, What went wrong, Action items. 2. 400–700 words. 3. States the correct incident duration (as hours+minutes or total minutes), and both the start and end times from the sources. 4. States the exact failed-payment count and affected-customer count from the sources. 5. Root cause section mentions an expired certificate; Detection section mentions customers/tweets/support and the alert/threshold problem. 6. Blameless: the departed employee is not named; no 'fault', 'blame', 'careless', 'negligent' wording. 7. At least 4 action-item bullets, every one containing 'TBD', and no person names in the Action items section. 8. No invented numbers: every number in the text must appear in the source files (a few small integers are whitelisted).
Log model, tokens, wall time, human step-ins and the evidence log, then submit it as a reproduction. A different model? Submit a head-to-head rerun.

How runs are scored: Methodology.

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Informational checks (not scored)

Reported with the run for context. They do not affect the score, the outcome or the rankings.

No invented numbers strict (did not pass): Moved out of the scored rubric on 2026-10-17: the task never defined this check, and the loosened version accepted most numbers. Strict result shown for reference. [19, 26, 32, 21, 21, 32]

Automated checks

Trust 80% comes from these checks (how Trust % works).

Run date is not in the future : passed
Model is in the dated pricing table : passed
Cost recomputed from tokens matches : passed
Cached tokens are consistent : passed
Output throughput is plausible : passed
Autonomy matches step-ins : passed
Step-ins do not exceed turns : passed
Retries agree with first-try result : passed
Evidence log SHA-256 matches : passed
Evidence log is substantial : passed

Evidence log

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  "result": "I've written `postmortem.md` from the two input files only. It has the eight required sections in the required order and comes to about 640 words of prose (681 if you count the table's `|` characters).\n\n- **Duration:** customer impact lasted 1 hour 35 minutes (09:12 to 10:47 UTC), from the first certificate errors to the payment success rate recovering to 98.6%. I also worked out the time gaps used in the Detection and What went well sections:\n  - The incident was declared 32 minutes after onset.\n  - Support escalated to on-call 26 minutes after onset.\n  - The root cause was found 21 minutes after the incident was declared.\n  - The rollout took 21 minutes.\n- **Numbers:** all copied as they appear in the sources: 98.7% falling to 41% then recovering to 98.6%, 2,314 failed attempts, 1,870 customers affected, 612 retried successfully, and the alert threshold of <10%.\n- **Blameless:** no names appear anywhere. People are described by role (incident commander, responder, engineer), and the person who left is only mentioned as \"one individual\". The root cause is described as a process gap, which is how the chat framed it.\n- **Action items:** these are the four from the chat. Each has an owner role and `Due: TBD`. I took out an offboarding-checklist item I had drafted, because nothing in the sources supports it.\n- **Conflicting times:** where the two files disagree by a minute or two, I used the timeline file. For example, it says the incident was declared at 09:44 and the deploy started at 10:20, while the chat shows 09:45 and 10:22. The one exception is root-cause identification, which I gave as 10:03\u201310:05 to cover the chat message and the timeline entry.",
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