Quickstart

This guide walks you through creating a minimal harness from scratch.

Prerequisites

An AI client that supports Agent Harnesses (see Clients)
Basic familiarity with markdown

Step 1 — Create the harness directory

mkdir my-first-harness
cd my-first-harness

Step 2 — Write HARNESS.md

HARNESS.md is the only required file. Create it now:

---
name: Writing Assistant
description: Helps draft, edit, and improve written content.
---

You are a writing assistant. Help the user draft, revise, and polish written content.
Adapt your tone to the context: formal for business documents, conversational for blog posts.

That’s a valid harness. You can stop here and install it in your client.

Step 3 — Add a skill (optional)

Create a skill to give your agent a specific, reusable capability:

mkdir -p skills/summarize

# skills/summarize/SKILL.md
---
name: Summarize
description: Condense a piece of text into a concise summary.
---

To summarize a document:
1. Read the full text provided by the user.
2. Identify the main argument or purpose.
3. Extract the 3–5 most important supporting points.
4. Write a summary of 3–5 sentences using plain language.
5. Do not add information that isn't in the source text.

Update HARNESS.md to reference the new skill:

---
name: Writing Assistant
description: Helps draft, edit, and improve written content.
---

You are a writing assistant. Help the user draft, revise, and polish written content.

**Skills**
- `summarize` — condense any text into a concise summary

Step 4 — Add a reference (optional)

References provide cross-skill context. Add a style guide:

mkdir references

# references/style-guide.md
---
description: Tone and formatting rules that apply to all written output.
---

- Use active voice wherever possible.
- Prefer short sentences (under 25 words).
- Avoid jargon unless the user's context is clearly technical.
- Headings use sentence case, not title case.

Update HARNESS.md:

---
name: Writing Assistant
description: Helps draft, edit, and improve written content.
---

You are a writing assistant. Help the user draft, revise, and polish written content.

**Skills**
- `summarize` — condense any text into a concise summary

**References**
- `style-guide.md` — tone and formatting rules for all output

Step 5 — Install the harness

Refer to your AI client’s documentation for how to install a local harness directory. Typically this involves pointing the client at the harness root folder.

What’s next

Best Practices — learn how to structure harnesses for maintainability
Optimizing Descriptions — write descriptions that help agents activate the right skills
Evaluating Harnesses — test that your harness behaves as expected

​Quickstart

​Prerequisites

​Step 1 — Create the harness directory

​Step 2 — Write HARNESS.md

​Step 3 — Add a skill (optional)

​Step 4 — Add a reference (optional)

​Step 5 — Install the harness

​What’s next