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/matrixfounder/agentic-development/hooks-creatornpx skills add MatrixFounder/Agentic-development --skill hooks-creatorgit clone --depth 1 https://github.com/MatrixFounder/Agentic-developmentWhat 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 | $0.00024 | $0.01335 |
| Opus 5 | $0.00012 | $0.00668 |
| Sonnet 5 | $0.00005 | $0.00267 |
| Haiku 4.5 | $0.00002 | $0.00134 |
Grade A, and why
hooks-creator 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 — 104 lines — stays where its author put it; the contents beside it link to each section on GitHub.
Hooks Creator
Purpose: Create robust, secure, and compliant Gemini CLI hooks that intercept and customize the agent's lifecycle (e.g., blocking tools, injecting context, logging).
[!WARNING] SECURITY CRITICAL:
- Strict JSON: Printing to
stdoutbreaks the CLI. Usestderrfor logs.- Injection Risks: BASH hooks MUST use
jq. Never usegrepon raw input.- Dependency Checks: Scripts MUST fail gracefully (exit 2) if deps like
jqare missing.
1. Red Flags (Anti-Rationalization)
STOP and READ THIS if you are thinking:
- "I'll use
grepto parse JSON in Bash because it's faster" -> WRONG. This is a security vulnerability. You MUST usejq. - "I'll just print a debug message to stdout" -> WRONG. This breaks JSON parsing. ALL logs must go to
stderr. - "I can skip the dependency check" -> WRONG. Scripts will fail silently. functionality. Always check for
jqor node modules. - "I'll use
exit 1for a denial" -> WRONG. Useexit 0with{"decision": "deny"}for structured feedback, orexit 2for system errors.
2. Capabilities
- Generate Bash hooks for simple logic (using
jq). - Generate Node.js hooks for complex logic or heavy JSON processing.
- Configure
settings.jsonwith correct matchers and event types. - Validate security and performance best practices.
3. Instruction Protocol
Phase 1: Analyze & Clarify
- Identify the Event: Map user intent to the correct Life Cycle Event.
- Example: "Stop me from committing secrets" ->
BeforeTool(triggered onwrite_file). - Example: "Add git history to context" ->
BeforeAgent(orSessionStart). - Example: "Add git history to context" ->
BeforeAgent(orSessionStart).
- Example: "Stop me from committing secrets" ->
- Analyize Clarity (Fast Path):
- Clear Request: If the user provides specific intent (e.g., "Block 'rm' commands"), SKIP clarification and proceed to implementation.
- Ambiguous Request: If vague (e.g., "Make it safer"), ask ONE clarifying question: "Do you want to block specific tools or scan content?"
- Select Implementation:
- Bash: For simple checks (grepping specific patterns, file existence).
- Node.js: For logic requiring array manipulation, complex JSON, or async calls.
What ships with it
10 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.
- examples/inject_context.sh 518 B runs code
- examples/log_tools.sh 567 B runs code
- examples/security_gate.sh 647 B runs code
- examples/settings_snippet.json 620 B
- examples/tool_filter.js 968 B runs code
- examples/usage_example.md 89 B
- examples/validate_response.js 721 B runs code
- references/best-practices.md 16 KB
- references/Gemini CLI Hooks.md 8.0 KB
- references/reference.md 12 KB
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 · 104 lines · 24 tokens per session scan A 809e9051c407
hooks-creator is a skill published in the GitHub repository MatrixFounder/Agentic-development (5 stars, last pushed 19d ago), licensed Apache-2.0. It adds 24 tokens to every session and 1,335 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 2026-08-31.
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