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

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

Trust 80%Fully autonomoussuccess · first tryCompare

Estimated cost: $0.12
Wall time: 18s
Human step-ins: 0
Outcome: Pass

Compare with other models on this task →

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 443329327). 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 3.12 (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: $0.117248. 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: $0.12
Wall time: 18s
Human step-ins: 0
Turns: 3

Model usage
Model	Input tok	Output tok	Cost
AClaude Opus 5.5anthropic/claude-opus-5.5effort default (no --effort flag) · thinking on	58,284	1,910	$0.12

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: 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.

Was this useful?

⇄ Rerun on another model

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

[
 {
  "duration_api_ms": 16618,
  "stop_reason": "end_turn",
  "session_id": "[REDACTED]",
  "total_cost_usd": 0.1172482,
  "usage": {
   "input_tokens": 6,
   "cache_creation_input_tokens": 8637,
   "cache_read_input_tokens": 49641,
   "output_tokens": 1910,
   "output_tokens_details": {
    "thinking_tokens": 188
   },
   "server_tool_use": {
    "web_search_requests": 0,
    "web_fetch_requests": 0
   },
   "service_tier": "standard",
   "cache_creation": {
    "ephemeral_1h_input_tokens": 8637,
    "ephemeral_5m_input_tokens": 0
   },
   "inference_geo": "global",
   "iterations": [
    {
     "input_tokens": 2,
     "output_tokens": 863,
     "cache_read_input_tokens": 19469,
     "cache_creation_input_tokens": 1314,
     "cache_creation": {
      "ephemeral_5m_input_tokens": 0,
      "ephemeral_1h_input_tokens": 1314
     },
     "type": "message"
    }
   ],
   "speed": "standard",
   "fallback_credit": null
  },
  "modelUsage": {
   "claude-opus-5-5": {
    "inputTokens": 6,
    "outputTokens": 1910,
    "cacheReadInputTokens": 49641,
    "cacheCreationInputTokens": 8637,
    "webSearchRequests": 0,
    "costUSD": 0.1172482,
    "contextWindow": 1000000,
    "maxOutputTokens": 128000,
    "thinkingTokens": 188,
    "canonicalModel": "claude-opus-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,
   "completed": 0,
   "failed": 0,
   "killed": {
    "parent": 0,
    "user": 0,
    "system": 0
   },
   "refused": {
    "depth_limit": 0,
    "concurrency_limit": 0,
    "budget": 0
   },
   "by_type": {}
  },
  "safety_stops": 0,
  "is_error": false,
  "num_turns": 3,
  "subtype": "success",
  "api_error_status": null,
  "result": "I've written `out/bills.json` with all 15 accounts billed. The grand total is **2355.99**, which is the sum of the bills after each was rounded to cents. I spot-checked the special cases below by hand against the raw reads, but there's no reference answer to compare against.\n\n| Account | kWh | Bill |\n|---|---|---|\n| AC-3100 | 494 | 151.17 |\n| AC-3113 | 607 | 185.29 |\n| AC-3126 | 699 | 213.06 |\n| AC-3139 | 688 | 209.74 |\n| AC-3152 | 684 | 208.53 |\n| AC-3165 | 617 | 188.30 |\n| AC-3178 | 172 | 60.22 |\n| AC-3191 | 664 | 202.49 |\n| AC-3204 | 292 | 90.59 |\n| AC-3217 | 193 | 65.53 |\n| AC-3230 | 161 | 57.44 |\n| AC-3243 | 158 | 56.68 |\n| AC-3256 | 790 | 240.53 |\n| AC-3269 | 816 | 248.38 |\n| AC-3282 | 583 | 178.04 |\n\nHow the special cases came out:\n- **Actual over estimated reads:** On 2026-09-30, AC-3152, AC-3243 and AC-3269 each had both an estimated and an actual read. In each case I used the actual read: 43605 not 43702, 31358 not 31244, and 83227 not 83027.\n- **Estimated reads kept:** Where no actual read existed for the date, the estimated read stood. That applied to several opening reads (AC-3126, AC-3139, AC-3191, AC-3204, AC-3256, AC-3282).\n- **Rollovers:** AC-3113 went from 99873 to 480, which is 607 kWh. AC-3230 went from 99995 to 156, which is 161 kWh.\n- **Meter exchange (AC-3178):** The old meter used 60 kWh (40958 to its final 41018) and the new meter used 112 kWh (11 to 123), for 172 kWh in total.\n\nEach bill is the tiered energy charge plus 30 days of standing charge, with 5% VAT on the whole. I did the arithmetic in exact decimals and rounded half-up only at the end.",
  "ttft_ms": 1994,
  "type": "result",
  "duration_ms": 16981,
  "uuid": "[REDACTED]",
  "ttft_stream_ms": 868,
  "time_to_request_ms": 256,
  "first_content_frame_ms": 869,
  "queued_turn_count": 0,
  "result_index": 0
 }
]