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

AClaude Sonnet 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: $0.06
Wall time: 19s
Human step-ins: 0
Outcome: Pass

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Rescored on 2026-10-28. Previous score: 85.0 / 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 13/14 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-sonnet-5.5: $0.064322. 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: $0.06
Wall time: 19s
Human step-ins: 0
Turns: 5

Model usage
Model	Input tok	Output tok	Cost
AClaude Sonnet 5.5anthropic/claude-sonnet-5.5effort default (no --effort flag) · thinking on	78,975	2,345	$0.06

Reproduce this run

Use the use case prompt on the use case page.
Same setup: Claude Sonnet 5.5 (anthropic/claude-sonnet-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. [26, 32, 21]

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 wrote `postmortem.md` with the eight H2 sections in the order you gave. It is 610 words by `wc`, which includes the title line and the Markdown symbols, and that is within the 400\u2013700 range.\n\n- **Durations I computed:**\n  - Customer impact ran 09:12 to 10:47, which is 95 minutes.\n  - Detection took 26 minutes to reach on-call and 32 minutes to a SEV-1 declaration.\n  - Finding the root cause took about 21 minutes from the SEV-1 declaration to 10:05.\n- **Blameless:** the person who left appears only as \"a single person who had since left the company\", and no one is named. The action-item owners are roles, each with a `TBD` due date.\n- **Estimate:** the \"about 10 minutes\" to issue the certificate is Lena's chat estimate, not a measured time. The post says \"estimated\".\n- **Small source difference:** the timeline logs the recovery at 10:47 and the chat says \"resolved\" at 10:48. I used 10:47 for the duration and mention both.\n- **Action items:** the four items come from the chat. I chose the owner roles myself, since the sources don't name any, so check that they fit your org.",
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