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.
npx agentmods add skills/google/adk-python/adk-unit-guidenpx skills add google/adk-python --skill adk-unit-guidegit clone --depth 1 https://github.com/google/adk-pythonWhat 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 | $0.00199 | $0.01577 |
| Opus 5 | $0.00100 | $0.00788 |
| Sonnet 5 | $0.00040 | $0.00315 |
| Haiku 4.5 | $0.00020 | $0.00158 |
Grade A, and why
adk-unit-guide 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.
How it starts
The opening of the file, as written. The whole thing — 150 lines — stays where its author put it; the contents beside it link to each section on GitHub.
ADK code unit guide
A unit guide is granular usage documentation for one code unit, deeper than what ships on adk.dev — so detail that would bloat the published documentation has somewhere to live. The reader wants to call the unit from an application, so lead with working code.
Unit guides focus on public APIs and caller-visible behavior. Do not discuss internal implementation details (such as private methods, internal state mechanisms, or unexported helpers).
Voice
Write to help the reader understand, not to instruct them from above.
- Give the reason, not only the rule. Whenever the guide states a constraint, a default, or a recommendation, say why it is that way. A reader who knows the reason can handle the case the guide did not anticipate.
- Do not decide for the reader. Phrasings such as "most applications never need this" or "you will rarely" tell people what they want. State the trade-off and let them choose.
- Explain at the caller's level. Explaining what happens is required; explaining the machinery that makes it happen is not. If an explanation needs a private symbol to make sense, it is pitched at the wrong layer.
- Length follows understanding. Brevity is not the goal. Where a reader would have a follow-up question, answer it. Where the sentence already lands, leave it.
- Problem before syntax. Say what the reader is trying to do, then show the code.
- Every heading has at least one sentence under it before the next heading, and every code block has a sentence introducing what it does.
Sentence-level rules, following the Google developer documentation style guide:
present tense, no contractions, no parentheticals (use commas), no bare "This"
as a subject, no e.g. or etc., no superlatives, sentence case in headings,
and no heading deeper than H3.
What the difference looks like
From the BaseNode guide. Before:
Most applications never subclass
BaseNode, so the sections that follow cover the settings first.
What ships with it
1 file beside SKILL.md in the same directory: the scripts, references and assets a skill reads on demand. Not counted in the per-session cost; read them before you install if any of them is executable.
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.
- 2d ago First seen · 150 lines · 199 tokens per session scan A 1578310ebb28
adk-unit-guide is a skill published in the GitHub repository google/adk-python (21,331 stars, last pushed 2d ago), licensed Apache-2.0. It adds 199 tokens to every session and 1,577 once invoked, about $0.0010 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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