command-development

Command Development for DeepSeek Harness

Note: Inside a plugin, commands live at com.deepseek.harness/commands/*.md. Project-level commands (outside a plugin) live at .agents/commands/*.md and load when the market plugin's project-layout scan is enabled. The frontmatter and body contract below is the same in both places.

Overview

Slash commands are frequently-used prompts defined as Markdown files that the agent executes during interactive sessions. Understanding command structure, frontmatter options, and dynamic features enables creating powerful, reusable workflows.

Key concepts:

• Markdown file format for commands
• YAML frontmatter for configuration
• Dynamic arguments and file references
• Dynamic context in commands
• Command organization and namespacing

Command Basics

What is a Slash Command?

A slash command is a Markdown file containing a prompt that the agent executes when invoked. Commands provide:

• Reusability: Define once, use repeatedly
• Consistency: Standardize common workflows
• Sharing: Distribute across team or projects
• Efficiency: Quick access to complex prompts

Critical: Commands are Instructions for the agent

Commands are written for agent consumption, not human consumption.

When a user invokes /command-name, the command content becomes the agent's instructions. Write commands as directives TO the agent about what to do, not as messages TO the user.

Correct approach (instructions for the agent):

Review this code for security vulnerabilities including:

- SQL injection
- XSS attacks
- Authentication issues

Provide specific line numbers and severity ratings.

Incorrect approach (messages to user):

This command will review your code for security issues.
You'll receive a report with vulnerability details.

The first example tells the agent what to do. The second tells the user what will happen but doesn't instruct the agent. Always use the first approach.