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 martinholovsky/claude-skills-generator --skill os-keychaingit clone --depth 1 https://github.com/martinholovsky/claude-skills-generatorWrote 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/martinholovsky/claude-skills-generator/os-keychain)<a href="https://agentmods.dev/skills/martinholovsky/claude-skills-generator/os-keychain"><img src="https://agentmods.dev/badge/skills/martinholovsky/claude-skills-generator/os-keychain/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/martinholovsky/claude-skills-generator/os-keychain"><img src="https://agentmods.dev/badge/skills/martinholovsky/claude-skills-generator/os-keychain.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 | $0.00000 | $0.04574 |
| Opus 5 | $0.00000 | $0.02287 |
| Sonnet 5 | $0.00000 | $0.00915 |
| Haiku 4.5 | $0.00000 | $0.00457 |
Grade A, and why
os-keychain 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 11d 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 — 611 lines — stays where its author put it; the contents beside it link to each section on GitHub.
OS Keychain Skill
name: os-keychain version: 1.1.0 domain: security/credential-storage risk_level: HIGH languages: [python, typescript, rust, go] frameworks: [keyring, security-framework, libsecret] requires_security_review: true compliance: [GDPR, HIPAA, PCI-DSS, SOC2] last_updated: 2025-01-15
MANDATORY READING PROTOCOL: Before implementing credential storage, read
references/advanced-patterns.mdfor cross-platform patterns andreferences/security-examples.mdfor platform-specific implementations.
1. Overview
1.1 Purpose and Scope
This skill provides secure credential storage using OS-native keychain services:
- Windows: Credential Manager (DPAPI-backed)
- macOS: Keychain Services (Secure Enclave integration)
- Linux: Secret Service API (GNOME Keyring, KWallet)
1.2 Risk Assessment
Risk Level: HIGH
Justification:
- Master keys and sensitive credentials stored
- Compromise exposes all dependent systems
- Platform API misuse leads to insecure storage
- Privilege escalation can access all credentials
Attack Surface:
- Inter-process communication (D-Bus, XPC)
- Access control misconfigurations
- Memory disclosure attacks
- Privilege escalation to access keychain
2. Core Principles
- TDD First - Write tests before implementing credential operations
- Performance Aware - Cache credentials, batch operations, minimize keychain calls
- Platform-native storage - Use OS keychain services for all credentials
- Access isolation - Unique service names prevent cross-contamination
- Secure by default - Reject insecure backends automatically
- Cross-platform support - Unified API across Windows, macOS, Linux
2.1 Security Principles
- NEVER store secrets in environment variables or files
- NEVER log credential values or access patterns with identifiers
- ALWAYS use platform-native keychain services
- ALWAYS validate application identity before credential access
- ALWAYS use unique service names per credential type
What ships with it
3 files 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.
- 11d ago First seen · 611 lines · 0 tokens per session scan A 1948cf7b2d56
os-keychain is a skill published in the GitHub repository martinholovsky/claude-skills-generator (45 stars, last pushed 9mo ago), licensed Unlicense. It costs nothing until one of its globs matches a file; then it loads 4,574 tokens. 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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