Claude Sonnet 5.5 (effort default (no --effort flag) · thinking off) on Bill a month of electricity from shuffled meter reads with estimates, rollovers and a meter exchange

AClaude Sonnet 5.5default · thinking off · Claude Code 2.1.299 (headless -p) · cloud · 2026-10-21 · by @bobsiopener

Trust 80%Fully autonomoussuccess · first tryCompare

Estimated cost: $0.05
Wall time: 9s
Human step-ins: 0
Outcome: Pass

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Exact prompt

# Bill September electricity from meter reads Inputs: `meters.csv` (each account's meters, including one exchange), `reads.csv` (actual "A" and estimated "E" reads, in no order) and `tariff.json`. Bill every account for the period from the opening read date to the closing read date in `tariff.json`. - Consumption = closing read minus opening read for each account. - When a meter has both an estimated and an actual read on the same date, use the actual read. An estimated read with no actual read for that date stands. - Meters have 5 dials and roll over from 99999 to 00000. A closing read below the opening read means the meter rolled over once. - If a meter was exchanged during the period, consumption = (old meter's final reading minus its opening read) + (new meter's closing read minus its initial reading). - Energy charge: the first `tier1_kwh` kWh at `tier1_rate`, the rest at `tier2_rate`. - Bill = energy charge + standing charge for 30 days, plus VAT on the whole. - Round each bill to cents half-up only at the end; the grand total is the sum of the rounded bills. Write `out/bills.json`: `{"kwh": {"<account_id>": <kWh>}, "bill_total": {"<account_id>": <amount>}, "grand_total": <amount>}`. ## 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.

Produce tiered electricity bills for 12-18 accounts from 30-50 shuffled reads. Some closing reads exist both as an estimate and as an actual, two meters roll over past 99999, and one account had its meter exchanged mid-month, so its consumption spans two meters. Keeping the estimate, missing the rollover, or subtracting across meters each gives a wrong kWh figure and bill. 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: consumption rollover_and_exchange bill_amounts grand_total

Setup notes: Batch 20 case v03-meter-reads-billing (offline, synthetic inputs, seed 52473958). 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 2.23 (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-sonnet-5.5: $0.047732. Score: 4/4. 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: $0.05
Wall time: 9s
Human step-ins: 0
Turns: 3

Model usage
Model	Input tok	Output tok	Cost
AClaude Sonnet 5.5anthropic/claude-sonnet-5.5effort default (no --effort flag) · thinking off	58,367	1,114	$0.05

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 off) via Claude Code 2.1.299 (headless -p), cloud.
It counts as a success only if it meets every success criterion: consumption rollover_and_exchange bill_amounts grand_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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  "stop_reason": "end_turn",
  "session_id": "[REDACTED]",
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   "output_tokens_details": {
    "thinking_tokens": 0
   },
   "server_tool_use": {
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   "service_tier": "standard",
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   "inference_geo": "global",
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     "cache_read_input_tokens": 19510,
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     "cache_creation": {
      "ephemeral_5m_input_tokens": 0,
      "ephemeral_1h_input_tokens": 912
     },
     "type": "message"
    }
   ],
   "speed": "standard",
   "fallback_credit": null
  },
  "modelUsage": {
   "claude-sonnet-5-5": {
    "inputTokens": 6,
    "outputTokens": 1114,
    "cacheReadInputTokens": 50478,
    "cacheCreationInputTokens": 7883,
    "webSearchRequests": 0,
    "costUSD": 0.047731800000000005,
    "contextWindow": 1000000,
    "maxOutputTokens": 128000,
    "thinkingTokens": 0,
    "canonicalModel": "claude-sonnet-5-5",
    "provider": "firstParty",
    "costBasis": "list"
   }
  },
  "permission_denials": [],
  "terminal_reason": "completed",
  "fast_mode_state": "off",
  "fast_mode_disabled_reason": "sdk_opt_in_required",
  "subagent_stats": {
   "spawned": 0,
   "requested": {
    "background": 0,
    "foreground": 0,
    "unset": 0
   },
   "started_in_background": 0,
   "max_depth": 0,
   "spawned_by_subagents": 0,
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   "killed": {
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   "refused": {
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   "by_type": {}
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  "safety_stops": 0,
  "is_error": false,
  "num_turns": 3,
  "subtype": "success",
  "api_error_status": null,
  "result": "I wrote `out/bills.json` with kWh and rounded bills for all 14 accounts. The grand total is 1,688.95. I haven't checked the figures against anything independent.\n\n- **Consumption:** it follows your rules. An actual read wins over an estimate on the same date, and a closing read below the opening read counts as one rollover. The one exchanged meter (AC-3243) uses the old meter's final reading plus the new meter's closing read minus its initial reading.\n- **Billing:** each bill is the energy charge plus 30 days of standing charge, with 5% VAT on the whole. Bills are rounded half-up to cents at the end, and the grand total is the sum of those rounded bills.\n- **Missing reads:** the script would have stopped with an error if any account lacked an opening or closing read for its meter. It didn't.",
  "ttft_ms": 2063,
  "type": "result",
  "duration_ms": 8668,
  "uuid": "[REDACTED]",
  "ttft_stream_ms": 1459,
  "time_to_request_ms": 264,
  "first_content_frame_ms": 1459,
  "queued_turn_count": 0,
  "result_index": 0
 }
]