What's the Difference Between Skills and App Rules?

Skills and App Rules both shape how your agent behaves, but they work at different levels. Skills teach an agent how to do something. App Rules enforce what an agent is allowed to do by blocking or tagging specific tool calls at the system level. Think of skills as training materials and app rules as security policies.

The Key Difference at a Glance

What Skills Do

A skill is a reusable set of instructions — and optionally templates and scripts — that teaches an agent how to do a specific task your way. When the agent encounters a task matching a skill's description, it loads the skill and follows the instructions inside.

Skills can include step-by-step processes, templates, domain knowledge, or executable scripts. Their superpower: they can improve over time. When you correct your agent, it can update the relevant skill so it does it right next time.

Use a skill when

• You have a multi-step process the agent should follow every time

• You need specific templates or formats the agent should reuse

• You have domain knowledge that's too long for the system prompt

• The instructions only apply sometimes — skills load on demand and save tokens

What App Rules Do

App Rules don't teach the agent anything — they enforce hard boundaries on what tool calls are allowed. Every tool call is checked against applicable rules. If a rule matches, the call is either:

• Blocked — denied entirely

• Tagged — allowed through but flagged for review

App Rules operate at the system level. The agent cannot decide to ignore them, override them, or work around them.

Use an app rule when

• You need to prevent agents from making specific tool calls (e.g., posting to a sensitive Slack channel)

• You want to block tool calls that include sensitive data (e.g., PII in an email body)

• You need an organization-wide restriction that applies to all agents and users

• You want to tag certain tool calls for audit or compliance review

• You need a restriction that even the agent creator cannot bypass

Can One Replace the Other?

No. A skill that says "never send messages to #general" is guidance the agent should follow, but nothing prevents it from doing so. An app rule that blocks messages to #general is hard enforcement — the tool call is denied at the system level.

For critical restrictions (compliance, data security, access control), use App Rules. For best results, use both together: a skill teaches the agent why something is restricted and how to handle related requests, while an app rule blocks the unsafe tool call as a safety net.

App Rule Scopes

App Rules can be set at two levels. A more-specific scope can only make things more restrictive, never less — if any matching rule blocks a call, it is blocked.

Quick Decision Guide

Related Docs

• Agent Skills — Full Reference

• App Rules — Full Reference

• App Policies — Overview

• Agents — Overview

Still Need Help?

If you're not sure which approach fits your use case, reach out to support at support@gumloop.com.