One Scenario, Four Tools

The same job can use a skill, an MCP connection, a sub-agent or custom instructions. Walk one scenario through all four.

The people, companies and numbers in this lesson are made up. Check any figure against your own situation before you rely on it.

Scenario: Maya wants each client's month-end summary drafted from a shared folder of exports and saved as a draft email.

Comparison Table

• Skill | holds the procedure and format | she writes it once | use for the how
• MCP connection | lets the agent read the folder and create a draft | needs permission setup | use for the where
• Sub-agent | does a side task in its own context, such as scanning ten exports | adds cost and moving parts | use when the work is big or separate
• Custom instructions | always-on preferences, such as tone | applies to every chat | use for habits, not procedures

Skills vs Tools

A skill isn't a tool. A tool does something, such as reading a file. A skill tells the agent how to do a task, and may call tools while it does. Maya uses a skill for the procedure and a read-only connection to the folder. She skips sub-agents until the volume needs them.

Exercise

• Take your first use case from Choose Your First Business Use Case.
• Fill the four rows for your own task.
• Pass condition: you can say in one sentence which row you'll use first and why.