Claude Haiku 5.5 (effort default (no --effort flag) · thinking on) on Seeded Monte Carlo retirement odds against a stated success threshold

AClaude Haiku 5.5default · thinking on · Claude Code 2.1.299 (headless -p) · cloud · 2026-10-20 · by @bobsiopener

Trust 80%Fully autonomoussuccess · first tryCompare

Estimated cost: $0.0059
Wall time: 24s
Human step-ins: 0
Outcome: Pass

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Exact prompt

# Seeded Monte Carlo retirement odds `input.json` holds the assumptions for a Monte Carlo retirement simulation (synthetic). Write `solve.py` (Python 3 standard library only) so that `python solve.py input.json answer.json` runs the simulation exactly as specified and writes the statistics. Because the random sequence is fixed by the seed, the answer is exact. We re-run it on fresh inputs, so do not hard-code anything. ## Input `seed`, `sims`, `years` (integers), `start_balance`, `annual_spend` (first-year spending), `mean_return`, `sd_return`, `mean_inflation`, `sd_inflation`, `success_threshold` (fractions). ## Rules 1. Create one generator `rng = random.Random(seed)` and use it for everything, in this order. Run simulations s = 0 .. sims-1 one after another. 2. Each simulation starts with balance = `start_balance` and spend = `annual_spend` (as floats). For each year y = 0 .. years-1: draw `r = rng.gauss(mean_return, sd_return)`, then `i = rng.gauss(mean_inflation, sd_inflation)` (both are drawn every year, in that order, before anything else), then balance -= spend. 3. If the balance is now below 0, the simulation **fails** in year y+1: its ending balance is 0 and it stops immediately (no more draws for it). Otherwise balance *= (1 + r) and spend *= (1 + i). 4. A simulation that never fails succeeds; its ending balance is the balance after the last year. 5. `success_rate` = successes / sims (round to 6 decimals). `meets_threshold` = (unrounded success rate >= `success_threshold`). `sims_failed` = number of failures. 6. Percentiles: sort all ending balances ascending (failed ones count as 0) into E; `pX` = E[int(X/100 * (sims - 1))] for X = 10, 50, 90 (round to 2 decimals). 7. `median_failure_year`: sort the failure years ascending into F and take F[int(0.5 * (len(F) - 1))]; `null` if nothing failed. 8. `best_sim` = index of the highest ending balance (lowest index on ties). `earliest_failure_sim` = index of the simulation that failed in the earliest year (lowest index on ties); `null` if nothing failed. ## Output `answer.json`: an object with keys `success_rate`, `meets_threshold`, `sims_failed`, `p10`, `p50`, `p90`, `median_failure_year`, `best_sim`, `earliest_failure_sim`. ## Chart (required visual) Also write `chart.svg` in the working directory: a static, self-contained SVG (root element `<svg>`, no scripts, no external images, fonts, stylesheets or links) that can be rendered headless. It must contain a percentile fan: `<polyline id="p10">`, `<polyline id="p50">`, `<polyline id="p90">`, each the 10th/50th/90th percentile end-of-year balance across simulations for each year (a failed simulation counts as 0 from its failure year). ## Scoring The `chart_svg_static` check (one more check, counted in partial credit) passes only if `chart.svg` exists after the fixture run, parses, has root `<svg>`, contains the ids above with the stated tags, and has no `<script>`, `<img>`/`<image>`, `<link>`, `<iframe>`/`<object>`/`<embed>`, `on*` handlers, or `href`/`src` pointing anywhere except `#...` or `data:`. Its drawing is not graded. Hidden checks (partial credit = fraction passed; all must pass): `success_rate_and_threshold` (rate within 0.000001, the other two exact), `percentiles` (within 0.011), `failure_stats` (exact), `best_sim` (exact) on the given input; `fresh_run_1` and `fresh_run_2`: every key on a fresh input (money within 0.011, rates within 0.011, counts and indexes exact). Each run has a 120-second limit.

With a fixed seed the success rate is exact only if the draw order (return then inflation, every year, stop on failure) and the percentile/tie rules are followed exactly; approximate simulations score near zero. 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).

These are synthetic test cases for comparing AI models, not financial advice.

Success criteria: 1. success_rate_and_threshold 2. percentiles 3. failure_stats 4. best_sim 5. fresh_run_1 6. fresh_run_2 7. chart_svg_static

Setup notes: Use Case Scout batch 9 case j02-retirement-monte-carlo (offline fixture). Prepared with batch9/prepare.sh; hidden key/tests kept outside the agent's work dir. Prompt = TASK.md verbatim. Scored with the scout's scorer: `python score.py WORKDIR KEYDIR`. Tools: Read/Write/Edit/Glob/Grep/Bash, web disabled. Single run, no retries. Visual output (chart.svg) rendered offline to PNG with google-chrome headless, network blocked, 1280x800 at ~3 s after load. Claude Code's own reported cost for claude-haiku-5.5: $0.005888. Score: 7/7. 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.

Output

Claude Haiku 5.5 (effort default (no --effort flag) · thinking on) on Seeded Monte Carlo retirement odds against a stated success thresholdSuccess

Metrics

Estimated cost: $0.0059
Wall time: 24s
Human step-ins: 0
Turns: 5

Model usage
Model	Input tok	Output tok	Cost
AClaude Haiku 5.5anthropic/claude-haiku-5.5effort default (no --effort flag) · thinking on	91,858	5,065	$0.0059

Reproduce this run

Use the use case prompt on the use case page.
Same setup: Claude Haiku 5.5 (anthropic/claude-haiku-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. success_rate_and_threshold 2. percentiles 3. failure_stats 4. best_sim 5. fresh_run_1 6. fresh_run_2 7. chart_svg_static
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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  "result": "I wrote `solve.py` in the work directory. It runs the simulation as specified and writes both `answer.json` and `chart.svg`. On the given input it produces these results:\n\n```json\n{\n  \"success_rate\": 0.824667,\n  \"meets_threshold\": false,\n  \"sims_failed\": 263,\n  \"p10\": 0.0,\n  \"p50\": 1473403.0,\n  \"p90\": 5177505.89,\n  \"median_failure_year\": 23,\n  \"best_sim\": 692,\n  \"earliest_failure_sim\": 294\n}\n```\n\nI ran it with `python3 -I solve.py input.json answer.json`. I also ran a second input with no failures; there the solver gave `median_failure_year` and `earliest_failure_sim` as `null`, as specified. I have not checked these numbers against an independent implementation.\n\nThe chart is a static SVG with three polylines (`p10`, `p50`, `p90`) for the per-year percentiles. The file parses as XML with root `<svg>` and has no scripts, images, links, or external references. I did not render it in a browser.\n\nChoices I made where the spec left room:\n- Failed simulations keep a balance of 0 from their failure year onward, so they count as 0 in the chart percentiles.\n- The chart's x-axis runs from year 0 (the start balance) to the final year.\n- `meets_threshold` compares the unrounded success rate, as specified.",
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 }
]