What is hmt-monte-carlo?

A Monte Carlo analysis tool for hydraulic models. Monte Carlo analysis repeatedly runs a model with varied inputs to estimate the likelihood of different outcomes.

Use it to sample uncertain hydraulic parameters and calculate exceedance probabilities.

It shows how uncertain input values can change the results instead of presenting one possibly misleading prediction.

How psu-efd/pyHMT2D configures Claude Code and Codex

Reuse

Borrowing it

Nothing to install: this file belongs to psu-efd/pyHMT2D. Take a copy, put it at the same path in your own repository, and replace the rules that are about this project with yours.

Copy the file

curl -O https://raw.githubusercontent.com/psu-efd/pyHMT2D/main/.agents/skills/hmt-monte-carlo/SKILL.md

Clone the repo

git clone --depth 1 https://github.com/psu-efd/pyHMT2D

Made for: Claude Code, Codex.

Wrote this? Show the measurements

A badge with what this costs and how it scanned, read live from this page, so it follows the numbers instead of freezing them. Markdown for a README, HTML for a documentation site or a project page.

README.md

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Your own site

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Or the 80×15 button, for a site that already has a row of RSS and ATOM ones. Only the verdict fits; the numbers stay here.

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Per session 46 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.

When invoked 713 The whole file, excluding the scripts and references it only reads on demand.

Security scan A 0 findings. A grade says what 26 rules found in the file — not that it is safe. Third-party audits

NVIDIA SkillSpector pass 7 Sept 2026

How audits are shown

Origin original No closer match found in the catalogue.

Token cost

What it costs to keep this loaded

Counted locally with the o200k_base tokenizer, which is exact for GPT models; Claude uses its own tokenizer and its counts differ. Treat this as one consistent yardstick across the catalogue rather than a bill. Prices are per million input tokens.

Model	Per session	Once invoked
Fable 5.1	$0.00046	$0.00713
Opus 5.5	$0.00018	$0.00285
Sonnet 5.5	$0.00009	$0.00143
Haiku 4.5	$0.00005	$0.00071

Measured 2mo ago against content hash ee3dffdbec22, method: parsed. Prices are Anthropic first-party input rates as of 2026-10-07, from the pricing page.

Security

Grade A, and why

hmt-monte-carlo scanned grade A with 0 findings against 26 rules in 11 categories — prompt injection, anti-refusal, data exfiltration, privilege escalation, supply chain, agent snooping, system-prompt leakage, SSRF and excessive agency — measured 2mo ago.

A static scan of the body, not an audit. Every finding is printed with the line that produced it so you can judge whether it matters here. A mod is markdown that instructs an agent; that is exactly why what it instructs is worth reading.

Nothing flagged

None of the 26 patterns this scan looks for appear in this file: no shell pipes, no recursive deletes, no credential paths, no hidden text, no instruction-override or anti-refusal phrasing, no agent-config snooping. That is not a guarantee, it is the absence of the things that are checkable.

.agents/skills/hmt-monte-carlo/SKILL.md · 70 lines

How it starts

The opening of the file, as written. The whole thing — 70 lines — stays where its author put it; the contents beside it link to each section on GitHub.

Run Monte Carlo uncertainty analysis on a hydraulic model.

Prerequisites

Project in a base_case/ subdirectory
Parameter uncertainty distributions defined by user
Solver paths configured in hmt_config.json

Steps

Check that a project is open. If not, ask the user to run /hmt-open pointing to base_case/<project_file>.
Show available materials.
```
hmt-cli get_materials
```
Ask the user for uncertain parameters. For each:
- Material name or BC ID
- Distribution: "truncated_normal" (default) or "uniform"
- For truncated_normal: mean, std, min, max
- For uniform: min, max

Build validated parameter specifications.

hmt-cli build_param_specs --args '{"specs": [
  {"type": "manning_n", "material_name": "<name>", "distribution": "truncated_normal",
   "mean": <mean>, "std": <std>, "min": <min>, "max": <max>},
  ...
]}'

Confirm the distributions with the user.

Ask for MC settings: number of samples (50–200), random seed (default 42), output directory (default ./mc_runs), parallel processes (default 1).

Generate samples.

hmt-cli generate_mc_samples --args '{"param_specs": <specs>, "n_samples": <N>, "random_seed": <seed>, "output_csv": "mc_samples.csv"}'

Show a preview of the first 5 sample rows.

Run Monte Carlo simulations.

hmt-cli run_monte_carlo --args '{"base_case_dir": "./base_case", "param_specs": <specs>, "n_samples": <N>, "n_processes": <procs>, "random_seed": <seed>, "sample_csv": "mc_samples.csv", "delete_cases": true, "output_dir": "<output_dir>"}'

Periodically show progress while waiting:

tail -20 mc_progress.log

Report: successful/failed runs, results JSON path.

Compute statistics. Ask for observation point coordinates if the user wants point statistics.

hmt-cli get_mc_statistics --args '{"results_json": "<path>", "observation_points": [{"name": "<name>", "x": <x>, "y": <y>}], "exceedance_probabilities": [99, 90, 50, 10, 1]}'

Present exceedance table: Point | P99 | P90 | P50 | P10 | P1

Read the full file on GitHub · 70 lines

Changes

What this file has done since we first saw it

Hashed on every crawl. A supply-chain change to an agent config is a question of when, not whether, so the history is kept rather than the latest state alone.

2mo ago First seen · 70 lines · 46 tokens per session scan A ee3dffdbec22

Subscribe to this mod's changes

hmt-monte-carlo is a skill published in the GitHub repository psu-efd/pyHMT2D (134 stars, last pushed 2mo ago), licensed MIT. It adds 46 tokens to every session and 713 once invoked, about $0.0002 per session on Opus 5.5. A static security scan graded it A with 0 findings. No closer match exists in the catalogue, so it is treated as the original; first seen 2026-08-30.

Analytics and metrics Scientific agentic ai automation computational-hydraulics hec-ras srh-2d

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pyHMT2D: Skill for Claude Code