Agents

---
title: "Install the M3 agent skill"
description: "How m3 init and m3 setup install the testing-with-m3 agent skill, and how to install it yourself."
---

# Install the M3 agent skill

The `testing-with-m3` skill tells a coding agent what M3 is, how to write and
run a first direct test, and which M3 documentation page to read next. Its
`references/` directory is a copy of the M3 documentation for one release, so
the agent reads documentation that matches the M3 you installed.

## Automatic installation

`m3 init` and `m3 setup` install the skill into the project when it is
missing, and update it when it was installed for a different M3 release. They
run this command from the project root, with `VERSION` replaced by the output
of `m3 --version`:

```sh
npx --yes skills@1.7.0 add sineframe/m3#vVERSION --skill testing-with-m3 --agent universal claude-code -y
```

The command needs Node.js and Git. It installs the skill only at
`.agents/skills/testing-with-m3/`, creates a `.claude/skills/testing-with-m3`
link, and records the source and release in `skills-lock.json`. The skills
CLI version is pinned to 1.7.0, and telemetry is disabled for this command.
Commit those files if every contributor should get the skill.

M3 does not run the command when:

- you pass `--no-skill` to `m3 init` or `m3 setup`;
- any of `CI`, `GITHUB_ACTIONS`, `GITLAB_CI`, `BUILDKITE`, `CIRCLECI`,
  `JENKINS_URL`, `TF_BUILD`, `TEAMCITY_VERSION`, `BITBUCKET_BUILD_NUMBER`, or
  `CODEBUILD_BUILD_ID` is set to a non-empty value;
- you run `m3 setup` in a directory without `m3.toml`;
- M3 is installed for development (editable). Installation is skipped, and M3
  prints `Agent skill: skipped for a development install of M3. To install it, run:`
  followed by:

  ```sh
  npx --yes skills@1.7.0 add sineframe/m3#vVERSION --skill testing-with-m3 --agent universal claude-code -y
  ```
- a `testing-with-m3` skill that M3 did not install already exists in the
  project or in your home directory. M3 prints the command to replace it.

If `npx` is missing or the command fails, M3 prints the command and finishes
setup normally.

## Install it yourself

Run the command above with your M3 version. To install it globally, use:

```sh
npx --yes skills@1.7.0 add sineframe/m3#vVERSION --skill testing-with-m3 --agent universal claude-code -g
```

M3 does not update a global installation, so rerun the command after upgrading
M3.

[Read the skill source.](../../../../skills/testing-with-m3/SKILL.md)