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 skills add GuitarAlchemist/ga --skill annotations-guidancegit clone --depth 1 https://github.com/GuitarAlchemist/gaWrote 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.
[](https://agentmods.dev/skills/guitaralchemist/ga/annotations-guidance)<a href="https://agentmods.dev/skills/guitaralchemist/ga/annotations-guidance"><img src="https://agentmods.dev/badge/skills/guitaralchemist/ga/annotations-guidance/github.svg" alt="Measured on agentmods" height="20"></a>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.
<a href="https://agentmods.dev/skills/guitaralchemist/ga/annotations-guidance"><img src="https://agentmods.dev/badge/skills/guitaralchemist/ga/annotations-guidance.svg" alt="Reviewed on agentmods" width="80" height="20"></a>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 | $0.00035 | $0.01005 |
| Opus 5 | $0.00017 | $0.00502 |
| Sonnet 5 | $0.00007 | $0.00201 |
| Haiku 4.5 | $0.00003 | $0.00101 |
Grade A, and why
Annotations Guidance 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 8d 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 — 138 lines — stays where its author put it; the contents beside it link to each section on GitHub.
Annotations Guidance Skill
Purpose
This skill provides guidance on when to use JetBrains.Annotations vs native System.Diagnostics.CodeAnalysis attributes in C# 14 / .NET 10+ codebases with nullable reference types enabled.
Core Principle
With nullable reference types enabled (<Nullable>enable</Nullable>), most JetBrains nullability annotations are redundant. Prefer native C# nullability syntax and System.Diagnostics.CodeAnalysis attributes.
JetBrains Annotations to KEEP
[PublicAPI]
- No native equivalent
- Valuable for API documentation and static analysis tools
- Indicates a type or member is part of the public API
- Action: Keep all usages
[Pure]
- No native equivalent
- Indicates a method has no side effects
- Action: Keep all usages
[MustUseReturnValue]
- No native equivalent
- Indicates the return value should not be discarded
- Action: Keep all usages
JetBrains Annotations to REMOVE (Redundant)
[NotNull]
- Native equivalent: Non-nullable reference types (no
?suffix) - Example:
string nameis already non-nullable - Action: Remove - redundant with nullable reference types
[CanBeNull]
- Native equivalent: Nullable reference types (
?suffix) - Example:
string? nameis already nullable - Action: Remove - use
?suffix instead
[ItemNotNull]
- Native equivalent: Non-nullable element types
- Example:
IEnumerable<string>(elements are non-nullable) - Action: Remove - redundant
[ItemCanBeNull]
- Native equivalent: Nullable element types
- Example:
IEnumerable<string?>(elements are nullable) - Action: Remove - use
?suffix on element type
JetBrains Annotations to REPLACE
[ContractAnnotation]
Replace with native System.Diagnostics.CodeAnalysis attributes:
| JetBrains Pattern | Native Replacement |
|---|---|
"null => halt" |
[DoesNotReturn] on throw helper |
"value:null => false" |
[NotNullWhen(true)] on out param |
"=> true, value:notnull" |
[NotNullWhen(true)] on out param |
"=> false, value:null" |
[MaybeNullWhen(false)] on out param |
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.
- 8d ago First seen · 138 lines · 35 tokens per session scan A fcb5a65bc7dd
Annotations Guidance is a skill published in the GitHub repository GuitarAlchemist/ga (2 stars, last pushed today), licensed MIT. It adds 35 tokens to every session and 1,005 once invoked, about $0.0002 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 2026-09-03.
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