Prompts vs Skills vs Agents for Marketing Work
Prompts request outputs. Skills preserve methods. Agents coordinate decisions and tools across a goal.
Use a prompt for one request, a skill for a repeatable method, and an agent when work requires several decisions or tools.
Confusing these layers creates giant prompts that are hard to test, reuse, or update.
Prompt
A prompt describes current task and desired result.
Review this landing-page draft for clarity. Audience is operations leaders at 50-200 person SaaS companies. Return five specific edits.
Prompt works when context is local, stakes are low, and method does not need to survive current conversation.
Skill
A skill packages a method so several agents and people can apply same standard.
skills/landing-page-review/
├── SKILL.md
├── references/rubric.md
└── examples/review.md
Skill defines:
- When to use it
- Required inputs
- Review sequence
- Evidence rules
- Output format
- Failure and stop conditions
Agent Skills specification uses SKILL.md as entry point and supports progressive disclosure through linked references. That keeps core instruction small while detailed material remains available when needed.
Agent
Agent owns goal requiring several steps:
Goal: improve landing-page conversion hypothesis quality.
1. Read audience context.
2. Analyze page and current evidence.
3. Run landing-page review skill.
4. Generate test hypotheses.
5. Score hypotheses against experiment rubric.
6. Prepare review packet.
Agent decides which skill or tool to use and when to stop. Permissions should match goal. Drafting hypotheses does not require access to deploy site changes.
Workflow
Workflow describes operating process around agent:
- Trigger
- Owner
- Inputs
- Agent or skills used
- Approval points
- Destination
- Measurement
- Recovery path
Workflow may be fully deterministic or contain an agentic step. Calling every workflow an agent hides where decisions occur.
Decision table
| Need | Use |
|---|---|
| One output from current context | Prompt |
| Repeatable task with stable standard | Skill |
| Several decisions or tools toward a goal | Agent |
| Team process with owners and approvals | Workflow |
Common failure: giant prompt
Large prompts often mix brand context, task instructions, scoring rules, examples, tool policy, and output schema. One edit can break unrelated behavior.
Split by ownership:
- Context states facts and constraints.
- Skill states method.
- Prompt states current request.
- Agent states sequence and decisions.
- Workflow states people, approvals, and system boundaries.
Common failure: agent without eval
An agent that runs repeatedly needs a fixed way to judge results. Keep a small benchmark set of representative inputs and expected properties. Test instruction changes against same set before adopting them.
Practical migration
Start with prompts already used every week. Extract shared method into one skill. Add examples only when they teach a concrete boundary. Compose agent after two or more skills need coordination.
Architecture should grow from repeated work. Empty agent folders and generic prompt libraries create maintenance without improving output.