Writing Hookify Rules

Writing Hookify Rules is an official Anthropic skill from the claude-plugins-official repository. Its direct primary source is plugins/hookify/skills/writing-rules; the Smithery candidate uses the different slug writing-hookify-rules for that official directory. According to the provider, the skill helps users create a hookify rule, write a hook rule, configure hookify, add a hookify rule, and understand hookify rule syntax and patterns. It is a text-based working guide for Claude Code, not an independent hook runner, a security product, or a guarantee that every generated rule fits a particular codebase.

Purpose and workflow

According to the provider, hookify rules are Markdown files with YAML frontmatter. The frontmatter identifies the rule, controls whether it is enabled, selects the event that triggers it, and supplies either a simple pattern or a set of advanced conditions. The Markdown text after the frontmatter becomes the message shown when the rule matches. The skill therefore helps turn an intention such as warning about risky commands into a configuration that a team can read, review, test, and adapt.

When creating a rule, the documented approach starts with a unique and descriptive name. The provider recommends action-oriented kebab-case names for warnings, blocks, checks, or requirements. The enabled field turns a rule on or off without deleting its file. The event field selects the trigger scope. The documented event types cover Bash commands, file changes, session stops, submitted prompts, or all events. An optional action field distinguishes a warning, which permits the operation, from a block, which can prevent a tool operation or stop a session.

Simple patterns and advanced conditions

A simple pattern is a regular expression according to the provider. For Bash events it is matched against the command, and for file events it is matched against new text. This is sufficient for one well-defined signal, such as a filename pattern or a known code construct. The skill also documents an advanced format for cases where several aspects must be checked together. Conditions can inspect different fields and use different operators, such as a file path together with newly written content. All conditions must match before the rule triggers.

The documented fields include command for Bash and file_path, new_text, old_text, and content for file events. The provider describes regular-expression matching, substring presence, exact equality, substring exclusion, prefix checks, and suffix checks. This makes a rule more expressive, but it also increases the need for realistic testing. A broad pattern can interrupt legitimate work, while a narrow pattern can miss important cases. The skill is consequently most useful as a writing and review aid, not as a substitute for examining actual inputs in the target project.

Messages and safety boundaries

The provider recommends that a rule message explain what was detected, why it may be problematic, and what safer practice could be used instead. A useful warning should not merely emit a keyword. It should make the relevant operation, its possible effect on source code, data, or permissions, and a safer alternative understandable. The message body may use Markdown because it is displayed to Claude by Hookify. This catalog description intentionally avoids unsupported formatting markers so that it renders cleanly on Skill Road.

Hookify does not grant permissions to a rule and does not prove that a proposed pattern is safe. Rules can warn or block only according to the input they inspect. Teams must separately assess Claude Code permissions, local files, network access, secrets, privacy requirements, and prompt-injection scenarios. Credentials, tokens, personal information, and production values should never be placed in example rules or warning messages. Before enabling a block, test an appropriate exception path so necessary maintenance is not prevented without a recoverable workflow.

Team context and limitations

The skill is suitable for developers and maintainers who want to document recurring guardrails for agentic coding workflows. A rule can become a versioned team convention when its scope, trigger, message, and expected response are understood. Local or sensitive adaptations require deliberate decisions about storage and sharing. Every rule belongs in a controlled test loop: harmless inputs should remain unaffected, expected matches should produce an intelligible message, and blocks should never be treated as the only security control.

The only source used for this entry is Anthropic's official plugins/hookify/skills/writing-rules path in the public claude-plugins-official repository. The repository identifies Apache-2.0 as its license. Skill Road lists this as an external, verified Anthropic skill and stores no GitHub stars because the Skill model has no corresponding field. This entry states no concrete prices or account terms. According to the provider, the skill documents rule files, frontmatter, events, patterns, conditions, and messages; actual availability and execution depend on the Claude Code environment, its permissions, and careful human review.