python-runner

A workflow for solving computations or transformations by writing a short Python script and printing its result. The script runs in an isolated environment without network access.

In plain words
What is it for?
It is for calculations and data transformations that can be handled with standard Python code.
Why use it?
It provides a repeatable way to process supplied data while limiting access to the surrounding system.

Skill for Claude CodeCodex

Install

Getting it into your agent

One page per mod, every tool's command on it. A separate URL per tool would split the same page into five that compete with each other.

agentmods
npx agentmods add skills/richardhe-fundamenta/practical-gcp-examples/python-runner
Any agent
npx skills add richardhe-fundamenta/practical-gcp-examples --skill python-runner
Clone the repo
git clone --depth 1 https://github.com/richardhe-fundamenta/practical-gcp-examples

Made for: Claude Code, Codex.

Per session 24 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 252 The whole file, excluding the scripts and references it only reads on demand.
Security scan A 0 findings. Scan, not verified.
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.

ModelPer sessionOnce invoked
Fable 5 $0.00024 $0.00252
Opus 5 $0.00012 $0.00126
Sonnet 5 $0.00005 $0.00050
Haiku 4.5 $0.00002 $0.00025

Measured 2d ago against content hash b7b613761426, method: parsed. Prices are Anthropic first-party input rates as of 2026-08-30, from the pricing page.

Security

Grade A, and why

python-runner 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 2d 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.

a2a-with-gke-sandbox/skills/python-runner/SKILL.md · 25 lines

What it actually says

python-runner

When the user asks for a computation or transformation:

  1. Write a short, self-contained Python script that prints its result to stdout.
  2. Call the run_code tool with that script as code.
  3. Report the stdout back to the user as the answer.

Constraints (the sandbox enforces these structurally):

  • No network access. Standard library only unless the runtime image provides a package.
  • The script must print() its text result — stdout is returned.
  • Files you write to the working directory are returned to the user as attachments; for binary results (images, etc.) write a file rather than printing bytes.
  • Uploaded files are available by name (e.g. open("data.csv")). Never hardcode or reconstruct a file's contents from memory — if a file you need isn't in the working directory, ask the user to attach it rather than inventing the data.
  • If run_code returns an error, read it, fix the script, and call run_code again.
  • Keep scripts short and deterministic.
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.

  1. 2d ago First seen · 25 lines · 24 tokens per session scan A b7b613761426

Subscribe to this mod's changes

python-runner is a skill published in the GitHub repository richardhe-fundamenta/practical-gcp-examples (54 stars, last pushed 16d ago), licensed MIT. It adds 24 tokens to every session and 252 once invoked, about $0.0001 per session on Opus 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.

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