Writing Hookify Rules
AnthropicOfficialPublished by Anthropic
- Skill
- Guidelines
- Automation and integrations
- Apache-2.0
- No issues found
AutoGineer summary
Written by AutoGineer from the skill’s own files, not by the author
Hookify allows you to define custom rules that monitor an agent's interactions with bash commands, file edits, stop events, and user prompts. By creating markdown files with YAML frontmatter in the .claude directory, you can trigger warnings or blocks based on specific patterns, helping to enforce best practices, prevent dangerous operations, or provide context-aware reminders during a session.
What it does
- Defines patterns to watch for in bash commands, file edits, and user prompts.
- Supports simple regex-based matching or complex multi-condition logic.
- Allows for custom warning messages to be displayed when a rule is triggered.
- Enables blocking of specific operations to prevent errors or security risks.
- Provides a mechanism for completion checklists before an agent stops.
- Uses dynamic loading so rules take effect immediately upon file creation or update.
When to use it
- When you need to prevent the execution of dangerous bash commands like rm -rf.
- When you want to warn developers about committing debug code like console.log.
- When you need to enforce project-specific workflows or checklists before stopping.
- When you want to restrict edits to sensitive files like .env or configuration files.
- When you need to provide guidance or reminders based on specific user prompts.
Advantages
- Highly flexible configuration using standard markdown and YAML.
- Rules are stored locally within the project for easy version control.
- Supports both simple regex and advanced multi-condition logic.
- Immediate feedback loop without needing to restart the agent.
- Non-destructive; rules can be toggled via the enabled flag.
Usage examples
- “Create a hookify rule to warn me whenever I try to use the rm -rf command.”
- The agent will generate a .claude/hookify.warn-rm-rf.local.md file with the appropriate bash event and regex pattern to trigger a warning.
- “How do I block edits to my .env file that include an API_KEY?”
- The agent will provide a multi-condition rule template that checks both the file_path and the new_text fields to block the edit.
Install
Download the skill as a ZIP:
https://mp-staging.autogineer.com/agent-skills/anthropics/writing-hookify-rules/downloadUnzip it into the cross-client skills folder of your project:
mkdir -p .agents/skills && unzip writing-hookify-rules.zip -d .agents/skills
Documentation by Anthropic
Writing Hookify Rules
Overview
Hookify rules are markdown files with YAML frontmatter that define patterns to watch for and messages to show when those patterns match. Rules are stored in .claude/hookify.{rule-name}.local.md files.
Rule File Format
Basic Structure
---
name: rule-identifier
enabled: true
event: bash|file|stop|prompt|all
pattern: regex-pattern-here
---
Message to show Claude when this rule triggers.
Can include markdown formatting, warnings, suggestions, etc.Frontmatter Fields
name (required): Unique identifier for the rule
Use kebab-case:
warn-dangerous-rm,block-console-logBe descriptive and action-oriented
Start with verb: warn, prevent, block, require, check
enabled (required): Boolean to activate/deactivate
true: Rule is activefalse: Rule is disabled (won't trigger)Can toggle without deleting rule
event (required): Which hook event to trigger on
bash: Bash tool commandsfile: Edit, Write, MultiEdit toolsstop: When agent wants to stopprompt: When user submits a promptall: All events
action (optional): What to do when rule matches
warn: Show message but allow operation (default)block: Prevent operation (PreToolUse) or stop session (Stop events)If omitted, defaults to
warn
pattern (simple format): Regex pattern to match
Used for simple single-condition rules
Matches against command (bash) or new_text (file)
Python regex syntax
Example:
event: bash
pattern: rm\s+-rfAdvanced Format (Multiple Conditions)
For complex rules with multiple conditions:
---
name: warn-env-file-edits
enabled: true
event: file
conditions:
- field: file_path
operator: regex_match
pattern: \.env$
- field: new_text
operator: contains
pattern: API_KEY
---
You're adding an API key to a .env file. Ensure this file is in .gitignore!Condition fields:
field: Which field to checkFor bash:
commandFor file:
file_path,new_text,old_text,content
operator: How to matchregex_match: Regex pattern matchingcontains: Substring checkequals: Exact matchnot_contains: Substring must NOT be presentstarts_with: Prefix checkends_with: Suffix check
pattern: Pattern or string to match
All conditions must match for rule to trigger.
Message Body
The markdown content after frontmatter is shown to Claude when the rule triggers.
Good messages:
Explain what was detected
Explain why it's problematic
Suggest alternatives or best practices
Use formatting for clarity (bold, lists, etc.)
Example:
⚠️ **Console.log detected!**
You're adding console.log to production code.
**Why this matters:**
- Debug logs shouldn't ship to production
- Console.log can expose sensitive data
- Impacts browser performance
**Alternatives:**
- Use a proper logging library
- Remove before committing
- Use conditional debug buildsEvent Type Guide
bash Events
Match Bash command patterns:
---
event: bash
pattern: sudo\s+|rm\s+-rf|chmod\s+777
---
Dangerous command detected!Common patterns:
Dangerous commands:
rm\s+-rf,dd\s+if=,mkfsPrivilege escalation:
sudo\s+,su\s+Permission issues:
chmod\s+777,chown\s+root
file Events
Match Edit/Write/MultiEdit operations:
---
event: file
pattern: console\.log\(|eval\(|innerHTML\s*=
---
Potentially problematic code pattern detected!Match on different fields:
---
event: file
conditions:
- field: file_path
operator: regex_match
pattern: \.tsx?$
- field: new_text
operator: regex_match
pattern: console\.log\(
---
Console.log in TypeScript file!Common patterns:
Debug code:
console\.log\(,debugger,print\(Security risks:
eval\(,innerHTML\s*=,dangerouslySetInnerHTMLSensitive files:
\.env$,credentials,\.pem$Generated files:
node_modules/,dist/,build/
stop Events
Match when agent wants to stop (completion checks):
---
event: stop
pattern: .*
---
Before stopping, verify:
- [ ] Tests were run
- [ ] Build succeeded
- [ ] Documentation updatedUse for:
Reminders about required steps
Completion checklists
Process enforcement
prompt Events
Match user prompt content (advanced):
---
event: prompt
conditions:
- field: user_prompt
operator: contains
pattern: deploy to production
---
Production deployment checklist:
- [ ] Tests passing?
- [ ] Reviewed by team?
- [ ] Monitoring ready?Pattern Writing Tips
Regex Basics
Literal characters: Most characters match themselves
rmmatches "rm"console.logmatches "console.log"
Special characters need escaping:
.(any char) →\.(literal dot)()→\(\)(literal parens)[]→\[\](literal brackets)
Common metacharacters:
\s- whitespace (space, tab, newline)\d- digit (0-9)\w- word character (a-z, A-Z, 0-9, _).- any character+- one or more*- zero or more?- zero or one|- OR
Examples:
rm\s+-rf Matches: rm -rf, rm -rf
console\.log\( Matches: console.log(
(eval|exec)\( Matches: eval( or exec(
chmod\s+777 Matches: chmod 777, chmod 777
API_KEY\s*= Matches: API_KEY=, API_KEY =Testing Patterns
Test regex patterns before using:
python3 -c "import re; print(re.search(r'your_pattern', 'test text'))"Or use online regex testers (regex101.com with Python flavor).
Common Pitfalls
Too broad:
pattern: log # Matches "log", "login", "dialog", "catalog"Better: console\.log\(|logger\.
Too specific:
pattern: rm -rf /tmp # Only matches exact pathBetter: rm\s+-rf
Escaping issues:
YAML quoted strings:
"pattern"requires double backslashes\\sYAML unquoted:
pattern: \sworks as-isRecommendation: Use unquoted patterns in YAML
File Organization
Location: All rules in .claude/ directory
Naming: .claude/hookify.{descriptive-name}.local.md
Gitignore: Add .claude/*.local.md to .gitignore
Good names:
hookify.dangerous-rm.local.mdhookify.console-log.local.mdhookify.require-tests.local.mdhookify.sensitive-files.local.md
Bad names:
hookify.rule1.local.md(not descriptive)hookify.md(missing .local)danger.local.md(missing hookify prefix)
Workflow
Creating a Rule
Identify unwanted behavior
Determine which tool is involved (Bash, Edit, etc.)
Choose event type (bash, file, stop, etc.)
Write regex pattern
Create
.claude/hookify.{name}.local.mdfile in project rootTest immediately - rules are read dynamically on next tool use
Refining a Rule
Edit the
.local.mdfileAdjust pattern or message
Test immediately - changes take effect on next tool use
Disabling a Rule
Temporary: Set enabled: false in frontmatter
Permanent: Delete the .local.md file
Examples
See ${CLAUDE_PLUGIN_ROOT}/examples/ for complete examples:
dangerous-rm.local.md- Block dangerous rm commandsconsole-log-warning.local.md- Warn about console.logsensitive-files-warning.local.md- Warn about editing .env files
Quick Reference
Minimum viable rule:
---
name: my-rule
enabled: true
event: bash
pattern: dangerous_command
---
Warning message hereRule with conditions:
---
name: my-rule
enabled: true
event: file
conditions:
- field: file_path
operator: regex_match
pattern: \.ts$
- field: new_text
operator: contains
pattern: any
---
Warning messageEvent types:
bash- Bash commandsfile- File editsstop- Completion checksprompt- User inputall- All events
Field options:
Bash:
commandFile:
file_path,new_text,old_text,contentPrompt:
user_prompt
Operators:
regex_match,contains,equals,not_contains,starts_with,ends_with
Files
- ATTRIBUTION.mdAdded by AutoGineer960 B
- LICENSELicence file added by AutoGineer11.1 KiB
- SKILL.md8.2 KiB
LICENSE
Apache License
Version 2.0, January 2004
http://www.apache.org/licenses/
TERMS AND CONDITIONS FOR USE, REPRODUCTION, AND DISTRIBUTION
1. Definitions.
"License" shall mean the terms and conditions for use, reproduction,
and distribution as defined by Sections 1 through 9 of this document.
"Licensor" shall mean the copyright owner or entity authorized by
the copyright owner that is granting the License.
"Legal Entity" shall mean the union of the acting entity and all
other entities that control, are controlled by, or are under common
control with that entity. For the purposes of this definition,
"control" means (i) the power, direct or indirect, to cause the
direction or management of such entity, whether by contract or
otherwise, or (ii) ownership of fifty percent (50%) or more of the
outstanding shares, or (iii) beneficial ownership of such entity.
"You" (or "Your") shall mean an individual or Legal Entity
exercising permissions granted by this License.
"Source" form shall mean the preferred form for making modifications,
including but not limited to software source code, documentation
source, and configuration files.
"Object" form shall mean any form resulting from mechanical
transformation or translation of a Source form, including but
not limited to compiled object code, generated documentation,
and conversions to other media types.
"Work" shall mean the work of authorship, whether in Source or
Object form, made available under the License, as indicated by a
copyright notice that is included in or attached to the work
(an example is provided in the Appendix below).
"Derivative Works" shall mean any work, whether in Source or Object
form, that is based on (or derived from) the Work and for which the
editorial revisions, annotations, elaborations, or other modifications
represent, as a whole, an original work of authorship. For the purposes
of this License, Derivative Works shall not include works that remain
separable from, or merely link (or bind by name) to the interfaces of,
the Work and Derivative Works thereof.
"Contribution" shall mean any work of authorship, including
the original version of the Work and any modifications or additions
to that Work or Derivative Works thereof, that is intentionally
submitted to Licensor for inclusion in the Work by the copyright owner
or by an individual or Legal Entity authorized to submit on behalf of
the copyright owner. For the purposes of this definition, "submitted"
means any form of electronic, verbal, or written communication sent
to the Licensor or its representatives, including but not limited to
communication on electronic mailing lists, source code control systems,
and issue tracking systems that are managed by, or on behalf of, the
Licensor for the purpose of discussing and improving the Work, but
excluding communication that is conspicuously marked or otherwise
designated in writing by the copyright owner as "Not a Contribution."
"Contributor" shall mean Licensor and any individual or Legal Entity
on behalf of whom a Contribution has been received by Licensor and
subsequently incorporated within the Work.
2. Grant of Copyright License. Subject to the terms and conditions of
this License, each Contributor hereby grants to You a perpetual,
worldwide, non-exclusive, no-charge, royalty-free, irrevocable
copyright license to reproduce, prepare Derivative Works of,
publicly display, publicly perform, sublicense, and distribute the
Work and such Derivative Works in Source or Object form.
3. Grant of Patent License. Subject to the terms and conditions of
this License, each Contributor hereby grants to You a perpetual,
worldwide, non-exclusive, no-charge, royalty-free, irrevocable
(except as stated in this section) patent license to make, have made,
use, offer to sell, sell, import, and otherwise transfer the Work,
where such license applies only to those patent claims licensable
by such Contributor that are necessarily infringed by their
Contribution(s) alone or by combination of their Contribution(s)
with the Work to which such Contribution(s) was submitted. If You
institute patent litigation against any entity (including a
cross-claim or counterclaim in a lawsuit) alleging that the Work
or a Contribution incorporated within the Work constitutes direct
or contributory patent infringement, then any patent licenses
granted to You under this License for that Work shall terminate
as of the date such litigation is filed.
4. Redistribution. You may reproduce and distribute copies of the
Work or Derivative Works thereof in any medium, with or without
modifications, and in Source or Object form, provided that You
meet the following conditions:
(a) You must give any other recipients of the Work or
Derivative Works a copy of this License; and
(b) You must cause any modified files to carry prominent notices
stating that You changed the files; and
(c) You must retain, in the Source form of any Derivative Works
that You distribute, all copyright, patent, trademark, and
attribution notices from the Source form of the Work,
excluding those notices that do not pertain to any part of
the Derivative Works; and
(d) If the Work includes a "NOTICE" text file as part of its
distribution, then any Derivative Works that You distribute must
include a readable copy of the attribution notices contained
within such NOTICE file, excluding those notices that do not
pertain to any part of the Derivative Works, in at least one
of the following places: within a NOTICE text file distributed
as part of the Derivative Works; within the Source form or
documentation, if provided along with the Derivative Works; or,
within a display generated by the Derivative Works, if and
wherever such third-party notices normally appear. The contents
of the NOTICE file are for informational purposes only and
do not modify the License. You may add Your own attribution
notices within Derivative Works that You distribute, alongside
or as an addendum to the NOTICE text from the Work, provided
that such additional attribution notices cannot be construed
as modifying the License.
You may add Your own copyright statement to Your modifications and
may provide additional or different license terms and conditions
for use, reproduction, or distribution of Your modifications, or
for any such Derivative Works as a whole, provided Your use,
reproduction, and distribution of the Work otherwise complies with
the conditions stated in this License.
5. Submission of Contributions. Unless You explicitly state otherwise,
any Contribution intentionally submitted for inclusion in the Work
by You to the Licensor shall be under the terms and conditions of
this License, without any additional terms or conditions.
Notwithstanding the above, nothing herein shall supersede or modify
the terms of any separate license agreement you may have executed
with Licensor regarding such Contributions.
6. Trademarks. This License does not grant permission to use the trade
names, trademarks, service marks, or product names of the Licensor,
except as required for reasonable and customary use in describing the
origin of the Work and reproducing the content of the NOTICE file.
7. Disclaimer of Warranty. Unless required by applicable law or
agreed to in writing, Licensor provides the Work (and each
Contributor provides its Contributions) on an "AS IS" BASIS,
WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or
implied, including, without limitation, any warranties or conditions
of TITLE, NON-INFRINGEMENT, MERCHANTABILITY, or FITNESS FOR A
PARTICULAR PURPOSE. You are solely responsible for determining the
appropriateness of using or redistributing the Work and assume any
risks associated with Your exercise of permissions under this License.
8. Limitation of Liability. In no event and under no legal theory,
whether in tort (including negligence), contract, or otherwise,
unless required by applicable law (such as deliberate and grossly
negligent acts) or agreed to in writing, shall any Contributor be
liable to You for damages, including any direct, indirect, special,
incidental, or consequential damages of any character arising as a
result of this License or out of the use or inability to use the
Work (including but not limited to damages for loss of goodwill,
work stoppage, computer failure or malfunction, or any and all
other commercial damages or losses), even if such Contributor
has been advised of the possibility of such damages.
9. Accepting Warranty or Additional Liability. While redistributing
the Work or Derivative Works thereof, You may choose to offer,
and charge a fee for, acceptance of support, warranty, indemnity,
or other liability obligations and/or rights consistent with this
License. However, in accepting such obligations, You may act only
on Your own behalf and on Your sole responsibility, not on behalf
of any other Contributor, and only if You agree to indemnify,
defend, and hold each Contributor harmless for any liability
incurred by, or claims asserted against, such Contributor by reason
of your accepting any such warranty or additional liability.
END OF TERMS AND CONDITIONS
APPENDIX: How to apply the Apache License to your work.
To apply the Apache License to your work, attach the following
boilerplate notice, with the fields enclosed by brackets "[]"
replaced with your own identifying information. (Don't include
the brackets!) The text should be enclosed in the appropriate
comment syntax for the file format. We also recommend that a
file or class name and description of purpose be included on the
same "printed page" as the copyright notice for easier
identification within third-party archives.
Copyright [yyyy] [name of copyright owner]
Licensed under the Apache License, Version 2.0 (the "License");
you may not use this file except in compliance with the License.
You may obtain a copy of the License at
http://www.apache.org/licenses/LICENSE-2.0
Unless required by applicable law or agreed to in writing, software
distributed under the License is distributed on an "AS IS" BASIS,
WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
See the License for the specific language governing permissions and
limitations under the License.
Requirements and compatibility
Written for: Claude Code, Claude apps
Works with: Claude Code, Claude apps, OpenAI Codex, GitHub Copilot, Cursor, Gemini CLI, Kiro, OpenCode, Goose, Amp, Roo Code, JetBrains Junie, Factory Droid, Devin (ex-Windsurf), Mistral Vibe, OpenHands, Letta
“Works with” means the tool reads the open Agent Skills format; a skill written for one tool may use features others lack.
Needs: Names Claude Code tools, Needs an API key, Needs Python
Security
No issues found by our static scan· No issues found
A static scan is not a guarantee. Skills are third-party content: review a skill before you let an agent use it.
Attribution and licence
- Published by
- Anthropic
- Publisher
- Anthropic (Official)
- Source
- anthropics/claude-plugins-official · plugins/hookify/skills/writing-rules · commit 0412be7
- Licence
- Apache License 2.0 (redistribution allowed)
- LICENSE (added by AutoGineer from plugins/hookify/LICENSE)
- ATTRIBUTION.md (written by AutoGineer)
- Synced
AutoGineer is not affiliated with or endorsed by Anthropic.
Download ZIP
The ZIP holds the skill’s files, its licence files and an ATTRIBUTION.md. Download writing-hookify-rules.zip