agentmods.dev

PostToolUseFailure

A failure hook that runs a Python script after any tool call fails.

In plain words
What is it for?
Use it to trigger project-state handling after failed tool calls. The script runs through Bash and does not stop the process if it cannot run.
Why use it?
It records or updates agent state when an operation does not succeed, so later work can account for the failure.

Hook

Part of the claude-dev-kit plugin — 23 skills, 33 agents, 9 hooks shipped together

11 17d ago A scan tokens not measured copy · 97% MIT
View the source file pillip/claude-dev-kit
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 hooks/pillip/claude-dev-kit/post-tool-use-failure
Clone the repo
git clone --depth 1 https://github.com/pillip/claude-dev-kit

Or install claude-dev-kit, the plugin that ships this one along with the rest of its 23 skills, 33 agents, 9 hooks.

Per session not measured What this adds to a session before it is invoked.
When invoked not measured Not applicable: nothing here is loaded into a session.
Security scan A 0 findings. Scan, not verified.
Origin 97% copy Near-identical to another mod in the catalogue.
Security

Grade A, and why

PostToolUseFailure 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 3d ago.

A static scan of the commands this hook runs, not an audit. A hook is shell that executes on your machine at the event it names, which is why every command in it is printed with what was found.

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.

Origin

This is a copy

97% identical to SubagentStart — 2 lines differ, which has more behind it and is treated as the original. This page carries a canonical link to it rather than competing with it.

hooks/hooks.json · 13 lines

What it actually says

{
  "PostToolUseFailure": [
    {
      "matcher": "*",
      "hooks": [
        {
          "type": "command",
          "command": "bash -c '[ -f \"$CLAUDE_PLUGIN_ROOT/project/.claude/hooks/agent_state.py\" ] && HOOK_ROOT=\"$CLAUDE_PROJECT_DIR\" python3 \"$CLAUDE_PLUGIN_ROOT/project/.claude/hooks/agent_state.py\" || true'"
        }
      ]
    }
  ]
}
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. 3d ago First seen · 13 lines scan A 689c36dc2ed5

Subscribe to this mod's changes

PostToolUseFailure is a hook published in the GitHub repository pillip/claude-dev-kit (11 stars, last pushed 17d ago), licensed MIT. Its token cost is not measured: a hook is shell that never enters the context. A static security scan graded it A with 0 findings. It is 97% identical to SubagentStart, differing in 2 lines, and is treated as a copy.

Code Generationai-agentsautonomous-codingclaudeclaude-codedeveloper-tools
Related

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Stop

Runs when the agent finishes a response, running an inline shell check. From openplanr/planr-pipeline.

openplanr/planr-pipeline · not measured

PostToolUse

Runs after a tool call finishes for Write and Edit tool calls, executing format_and_lint.sh. From supabase/supabase.

supabase/supabase · not measured

SessionStart

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google-gemini/gemini-cli · not measured

SessionStart

Runs when a session starts on startup, executing install_pkgs.sh. From supabase/supabase.

supabase/supabase · not measured

PreToolUse

Runs before the agent uses a tool for Bash tool calls, running an inline shell check. From apache/superset.

apache/superset · not measured