As we move deeper into the era of AI-native development, the “chat box” is quickly becoming the floor, not the ceiling. As a heavy user of Cursor, I’ve spent the last year thinking about how to move from simple prompt-response cycles to true agentic workflows.

The core of this evolution lies in how we manage the agent’s context. If you treat the system prompt like a junk drawer, the agent gets confused and your context window disappears. To solve this, I’ve leaned into the three-pillared system available in Cursor: Rules, Commands (Instructions), and Skills.

1. Rules: The Non-Negotiable Guardrails

Location: .cursor/rules/ 

Nature: Always-On & Permanent

Rules are your project’s “Constitution.” They define the non-negotiables—security protocols, code style, or architectural patterns that should never break.

The Trade-off: Rules are always “on.” They live in the system prompt for every interaction, which means they are “expensive” in terms of context window usage.

• Best Practice: Keep your rules tight and focused. If your rules list exceeds 300-400 lines, you’re likely over-engineering and bloating the prompt, which can lead to the agent ignoring middle-of-the-list instructions.
• Primary Use Case: Enforcing consistent code standards (e.g., “All components must use TypeScript strict mode”).
• Invocation: Automatic. Included in every interaction.

2. Commands: The Mission & Persona (Instructions)

Location: .cursor/commands/ 

Nature: Task-Specific & Manual

In the Cursor ecosystem, Instructions are essentially Commands. While Rules are the constraints, Commands are the “Mission.” They tell the agent who it needs to be and what it needs to accomplish right now.

Instead of re-typing complex workflows, you invoke a Command to set a specific persona (like “DevOps Lead”) or to provide a step-by-step playbook for a current task. This keeps the agent focused on the mission without the overhead of permanent rules.

• Primary Use Case: Executing specific workflows like /review-pr or /security-audit.
• Invocation: Manual. Triggered by the user using the / prefix in Chat or Composer.

3. Skills: Just-in-Time Intelligence

Location: .cursor/skills/ 

Nature: Dynamic & Modular

Skills represent the most advanced way to extend your agent: Progressive Disclosure. You don’t tell the agent how to do a complex data migration unless it actually needs to do one.

When you use Skills, the agent only knows the name and a quick summary of the skill initially. If the agent determines the skill is relevant to your current request, it “loads” the full capability. This is “just-in-time” intelligence that keeps the context window clean—the agent isn’t bothered with the intricacies of a data pipeline while it’s simply fixing a CSS bug.

• Primary Use Case: Specialized domain expertise (e.g., the humanizer skill for natural writing or complex third-party API integrations).
• Invocation: Dynamic. The agent autonomously decides when a skill is relevant and loads it on demand.

Strategic Comparison

The Bottom Line

We’re no longer just writing prompts; we’re designing how agents think. By keeping your Rules tight, your Commands focused on the mission, and your deep expertise modularized into Skills, you create an agent that is significantly more reliable and context-aware.