Frontmatter and Placeholder Reference

Complete reference for command file frontmatter fields and template placeholders.

Frontmatter Fields

---
description: "Short summary shown in /help list"  # RECOMMENDED
agent: build                   # Optional: build | plan | <custom-agent-name>
model: provider/model-id       # Optional: override default model
subtask: true                  # Optional: run as background subagent
---

description

Shown in the /help command list. Write as a 3-7 word imperative phrase.

Good: Run tests and fix failures Bad: This command runs tests

agent

Routes the command to a specific agent:

Rule: Use agent: plan whenever the command should never write files.

model

Overrides the default model for this command only.

model: anthropic/claude-3-5-haiku-20241022   # Fast, cheap — for simple tasks
model: anthropic/claude-sonnet-4-5-20250514  # Balanced
model: openai/gpt-4o                          # Alternative provider

Use a cheaper/faster model for subtasks that don’t need full reasoning.

subtask

When true, the command runs as a background subagent:

• Does NOT show intermediate messages
• Returns a single final output
• Cannot interact with the user during execution

Use for: lint checks, spell checks, coverage reports, search tasks. Do NOT use for: step-by-step workflows, anything requiring user input.

Template Placeholders

$ARGUMENTS

Everything passed after the command name, as a single string.

/review src/api.ts --depth=deep

→ $ARGUMENTS = "src/api.ts --depth=deep"

Rules:

• Use ONCE per template (not repeated)
• Wrap in an XML block to keep objective clean
• Use when argument structure doesn’t matter

$1, $2, $3

Positional arguments split by whitespace.

/migrate UserCard class-component

→ $1 = "UserCard", $2 = "class-component"

Use when: You need to distinguish two independent inputs (e.g., source and target).

!cmd

Injects the output of a shell command at template load time.

!`git log --oneline -20`
!`git status`
!`cat package.json | jq .dependencies`

Rules:

• Backtick-wrapped command: !`command`
• Executes in the current project directory
• Output is injected inline before the agent sees the prompt
• Use for: git state, file listings, environment info, build output

@filename

Injects the full content of a file.

@src/schema.ts
@prisma/schema.prisma
@.env.example

Rules:

• Path relative to project root
• Content injected inline
• Use for: schemas, configs, reference files the agent needs

XML Block Conventions

The recommended template structure uses XML blocks to organize content:

Template Skeleton

---
description: Do the thing
---

<summary>
You MUST [primary action].
You SHOULD [secondary action].
You MUST [success condition].
</summary>

<context>
!`some-command`
@some/file.ts
</context>

<target>
$ARGUMENTS
</target>

<objective>
You MUST accomplish [goal] using the context and target above.
</objective>