Claude Code Skills vs. Custom Agents: A Mental Model Based on Task Consistency

A Reddit post from a Claude Code user provides a clear mental model for distinguishing between skills and custom agents, based on practical experience after months of use.

The Core Distinction: Consistency vs. Judgment

The key question to ask is: does the task need consistency or judgment?

• Skills are for tasks that follow the same steps every time. The user's example is a /meeting skill that always runs the same sequence: extract notes, cross-reference attendees, create a structured note, and propose Todoist tasks. No deviation is needed.
• Custom Agents are for tasks that require reasoning. The example given is a trip planning agent that reads travel history, researches the destination, generates three route variants, and asks calibration questions. Every trip is different, so the agent adapts.

Additional Concepts from the Source

The original post also covers several related concepts for building agents in Claude Code:

• Parallel Subagents: Running tasks simultaneously, such as researching three competitors at the same time.
• Subagent Delegation: Offloading heavy context-gathering to keep the main workflow clean.
• Hooks as Personal Guardrails: Using PreToolUse and PostToolUse hooks to control agent behavior.
• Four Building Blocks in Enterprise AI Agents: The post maps common enterprise agent components to Claude Code concepts: CLAUDE.md corresponds to the system prompt, MCP to tool descriptions, memory to short/long-term storage, and skills to technical guardrails.

The full article with more details is linked in the source.