claude-code:hook

A reference for Claude Code hooks, which are automated actions that run when events such as tool use, prompts, session changes, or agent handoffs occur. It lists hook types, common uses, and configuration locations.

In plain words
What is it for?
Use it to run validation before tools execute, inspect results afterward, preprocess prompts, handle permissions, log sessions, or configure Claude Code automation.
Why use it?
It helps automate checks and responses around coding-agent activity and troubleshoot hooks that do not run as expected.

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/bendrucker/claude/hook
Any agent
npx skills add bendrucker/claude --skill hook
Clone the repo
git clone --depth 1 https://github.com/bendrucker/claude

Made for: Claude Code, Codex.

Per session 84 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 1,361 The whole file, excluding the scripts and references it only reads on demand.
Security scan B 1 finding. 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 $0.00084 $0.01361
Opus 5 $0.00042 $0.00681
Sonnet 5 $0.00017 $0.00272
Haiku 4.5 $0.00008 $0.00136

Measured 2d ago against content hash c2c5bf56056c, method: parsed. Prices are Anthropic first-party input rates as of 2026-08-30, from the pricing page.

Security

Grade B, and why

claude-code:hook scanned grade B with 1 finding 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.

Reads agent configuration directoriesmediumAgent snooping

.claude/, .codex/, .gemini/ hold keys, settings and other credentials a mod has no legitimate need for.

- `~/.claude/settings.json` - User-level (global)
plugins/claude-code/skills/hook/SKILL.md · 145 lines

How it starts

The opening of the file, as written. The whole thing — 145 lines — stays where its author put it; the contents beside it link to each section on GitHub.

Claude Code Hooks

Reference for creating and configuring Claude Code hooks. When uncertain about syntax or features, use the Agent tool with subagent_type='claude-code-guide' to consult official docs.

Hook Types

Type Trigger Use Cases
PreToolUse Before tool execution Validate inputs, block operations, modify parameters
PostToolUse After tool completes Check results, run linters, provide feedback
UserPromptSubmit When user sends message Pre-process input, add context
PermissionRequest Permission dialog appears Return a decision, notify a remote approver
Stop Agent finishes a turn Cleanup, save state
StopFailure Agent stops on failure Report the failure
SubagentStart / SubagentStop Subagent spawns / completes Process results
SessionStart / SessionEnd Session begins / ends Inject context, export state
PreCompact / PostCompact Around context compaction Save important state
Notification System notification Log events
TeammateIdle Teammate about to go idle Hand off work

Configuration Files

  • ~/.claude/settings.json - User-level (global)
  • .claude/settings.json - Project-level
  • .claude/settings.local.json - Local (not committed)
  • Plugin hooks: plugins/<name>/hooks/hooks.json

Hook Structure

{
  "hooks": {
    "PostToolUse": [
      {
        "matcher": "Edit|Write",
        "hooks": [
          {
            "type": "command",
            "command": "bun ./hooks/ox"
          }
        ]
      }
    ]
  }
}
Matcher Patterns
  • Simple: "Write", "Edit"
  • Multiple: "Edit|Write|MultiEdit"
  • With args: "Bash(npm:*)", "Bash(osascript:*)|Bash(open:*)"
  • MCP tools: "mcp__linear__create_issue"
  • Plugin MCP tools: "mcp__plugin_<plugin>_<namespace>__<tool>"
  • Claude AI MCP tools: "mcp__claude_ai_<DisplayName>__<tool>"
  • All three patterns: "mcp__linear__create_issue|mcp__plugin_linear_linear__create_issue|mcp__claude_ai_Linear__save_issue"

Read the full file on GitHub · 145 lines

Files

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.

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 · 145 lines · 84 tokens per session scan B c2c5bf56056c

Subscribe to this mod's changes

claude-code:hook is a skill published in the GitHub repository bendrucker/claude (16 stars, last pushed 2d ago), licensed MIT. It adds 84 tokens to every session and 1,361 once invoked, about $0.0004 per session on Opus 5. A static security scan graded it B with 1 finding (reads agent configuration directories). No closer match exists in the catalogue, so it is treated as the original; first seen 2026-08-30.

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