Claude Opus 5.5 (effort default (no --effort flag) · thinking on) on Audit a taxi firm's fares for night and holiday rates, mixed distance units and started waiting minutes

AClaude Opus 5.5default · thinking on · Claude Code 2.1.299 (headless -p) · cloud · 2026-10-22 · by @bobsiopener

Trust 80%Fully autonomoussuccess · first tryCompare

Estimated cost: $0.13
Wall time: 18s
Human step-ins: 0
Outcome: Pass

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Exact prompt

# Audit a taxi firm's December fares against the tariff Inputs: `trips.csv` (trip_id, date, start_time, distance, unit, waiting_seconds, claimed_fare), `tariff.json` and `office-summary.txt`. Every amount is in pounds. The tariff file is the record; where the summary disagrees with it, the tariff wins. Rules: - The night per-mile rate applies to a trip that starts at or after night_from or before night_to, or whose date is listed in holidays; otherwise the day rate applies. The rate for the whole trip follows its start. - Distances with unit km are converted to miles by dividing by km_per_mile. - Waiting is charged per started minute (61 seconds is 2 minutes). - Fare = flag_fall + miles x per-mile rate + waiting minutes x waiting_per_minute, rounded half-up to the nearest 0.10. - A trip is overcharged if claimed_fare is more than 0.05 above the correct fare, and undercharged if it is more than 0.05 below it. Write `out/fare-audit.json`: `{"fares": {"<trip_id>": <correct fare>, ...}, "overcharged": [<sorted trip_ids>], "undercharged": [<sorted trip_ids>], "total": <sum of correct fares>}` with every trip in `fares`. ## How this run works - Work on your own: nobody will answer questions in this task, and writing to `ask/` counts against the run. - Write only under `out/`. Create `out/` if it is missing. Inputs are synthetic; don't fetch anything from the network. - Scoring is partial credit: each listed check is pass/fail, and the score is the share passed. Numbers are compared to within 0.005 unless the task says otherwise.

Recompute each trip's fare from the tariff and flag over- and under-charges. Trips start exactly on the night-rate boundaries, some fall on holiday dates, some distances are logged in km, waiting time is charged per started minute, and fares round to the nearest 10p. Several drivers' claims were metered in the wrong unit, and an office summary says everything was correct and misstates the rate rules. 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: fares claim_flags fare_total

Setup notes: Batch 27 case c03-taxi-fare-audit (offline, synthetic inputs, seed 1737026400). Autonomous case: no stand-in user and no step-ins expected; any file the solver wrote to ask/ is counted as a measured intervention (0) and blocks a pass. Prompt = TASK.md verbatim. Hidden key kept outside the solver's work dir. Scored with the case's scorer (python3 score.py WORKDIR KEYDIR, absolute paths); pass = every check true and no ask/ files. Tools: Read/Write/Edit/Glob/Grep/Bash, web disabled. Single run, no retries. 1-min load average at scoring 0.21 (8 cores). Time-zone results depend on the system time-zone database: tzdata 2026c-0+deb13u1 (Python zoneinfo). Claude Code's own reported cost for claude-opus-5.5: $0.132958. Score: 3/3. Cost is an ESTIMATE: measured tokens x pricing.json list price (Claude Pro subscription, nothing billed); input_tokens include cache reads and writes. Single run.

Estimated cost List-price estimate; not actually billed.

Metrics

Estimated cost: $0.13
Wall time: 18s
Human step-ins: 0
Turns: 4

Model usage
Model	Input tok	Output tok	Cost
AClaude Opus 5.5anthropic/claude-opus-5.5effort default (no --effort flag) · thinking on	79,956	1,877	$0.13

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: fares claim_flags fare_total
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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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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  "permission_denials": [],
  "terminal_reason": "completed",
  "fast_mode_state": "off",
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  "subagent_stats": {
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   "requested": {
    "background": 0,
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  "subtype": "success",
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  "result": "I've written `out/fare-audit.json` with all 22 trips. The correct fares add up to **\u00a3534.30**. The office summary says takings were \u00a3587.45 and \"all fares checked and correct,\" but against the tariff, 8 trips were charged the wrong amount.\n\n**Overcharged (7):**\n\n| Trip | Claimed | Correct | Over by |\n|---|---|---|---|\n| TX-4150 | 37.50 | 24.70 | 12.80 |\n| TX-4143 | 54.60 | 35.30 | 19.30 |\n| TX-4156 | 35.90 | 24.10 | 11.80 |\n| TX-4228 | 11.80 | 8.80 | 3.00 |\n| TX-4167 | 16.10 | 12.40 | 3.70 |\n| TX-4191 | 15.10 | 12.50 | 2.60 |\n| TX-4201 | 8.80 | 8.50 | 0.30 |\n\n**Undercharged (1):** TX-4208 was claimed at 46.30, but the correct fare is 46.70.\n\nWhere the summary disagreed with the tariff, I followed the tariff:\n- **Night start:** the summary says night rate starts at 22:01, but the tariff says 22:00. So TX-4102 and TX-4213, which both start at 22:00, are charged at the night rate. A trip starting at exactly 06:00 (TX-4113) is charged at the day rate.\n- **Holidays:** the summary says only Christmas Day gets the holiday rate, but the tariff lists 26 December too. So every trip on the 26th is charged at the night rate.\n\nTX-4248 was claimed at 22.05 against a correct fare of 22.00. The difference is exactly 0.05, which is not *more than* 0.05, so it isn't flagged. I did the sums in exact decimal arithmetic so this edge case couldn't flip because of rounding error.",
  "ttft_ms": 2213,
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  "time_to_request_ms": 264,
  "first_content_frame_ms": 939,
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 }
]