Skill Frontmatter Configuration

Core

Create and configure custom slash commands and skills · Difficulty 3/5

frontmatterskillsconfigurationforkallowed-tools

Prerequisites

Skill files support YAML frontmatter that controls execution behavior, tool access, and user interaction.

Frontmatter Options

---
argument-hint: "migration name"
context: fork
allowed-tools:
  - write_file
model: haiku
---

context: fork

Runs the skill in an isolated sub-agent context:

Prevents verbose output from polluting the main conversation

Essential for exploration/analysis skills (e.g., codebase analysis, brainstorming alternatives)

Abandoned approaches in the fork don't influence subsequent implementation work

The fork returns only a summary to the main conversation

allowed-tools

Restricts tool access during skill execution (principle of least privilege):

Limit to file write operations to prevent destructive actions

Prevent accidental deletion or modification of unrelated files

Each skill gets only the tools it needs

argument-hint

Shows expected parameters during autocomplete:

Prompts developers for required parameters when they invoke the skill without arguments

Improves discoverability of skill parameters

Example: argument-hint: "migration name" tells the developer to provide a migration name

Key Takeaways

✓context: fork isolates skill execution from main conversation
✓allowed-tools restricts tool access for safety (principle of least privilege)
✓argument-hint prompts developers for required parameters
✓Use fork for exploration skills to prevent verbose output from polluting context

Glossary Terms

context: fork

A skill frontmatter option in Claude Code that runs the skill in an isolated sub-agent context with its own conversation history. Prevents verbose analysis or exploration output from polluting the main conversation context. The forked context is discarded when the skill completes.

Related Concepts

Plan Mode vs Direct Execution

Use plan mode for ambiguous requirements with multiple valid approaches