> ## Documentation Index > Fetch the complete documentation index at: https://docs.open4rena.ai/llms.txt > Use this file to discover all available pages before exploring further. # Skills > Package reusable instructions that you or the model can load when they apply. A skill is a Markdown file of instructions for one kind of task, such as cutting a release, writing a migration, or reviewing an API change. The model can list and search your skills by their short descriptions and load the full instructions only when a task calls for them. You can also run a skill yourself as a slash command. Write a skill when you find yourself giving o4 the same multi-step instructions again and again. For rules that should apply to every session in a project, use [project instructions](/configuration/project-instructions) instead. ## Create a skill Each skill is a folder with a `SKILL.md` file in it. The folder name is the skill's name. To make a skill for this project, create `.o4/skills/release-notes/SKILL.md`: ```markdown theme={null} --- description: Draft release notes from the commits since the last tag. --- # Release notes 1. Find the latest tag with `git describe --tags --abbrev=0`. 2. List the commits since that tag. 3. Group the changes under Added, Changed, and Fixed. 4. Write the notes to `RELEASE_NOTES.md`. Don't commit. Focus on: $ARGUMENTS ``` Start a new o4 session, then run it with: ```text theme={null} /release-notes user-facing changes only ``` o4 builds its list of skill slash commands when a session starts, so a skill you add by hand gets its slash command in the next session. The model can find it right away, because its `skill` tool reads the folders each time. You can also create one from `/skills`: choose **Create new skill**, enter a name, pick the location (project or user), and o4 writes a `SKILL.md` template and opens it in your editor. A skill created this way works as a slash command right away. ## Where skills live | Location | Folder | Available | | - | - | - | | Project | `.o4/skills//SKILL.md` | In this workspace, once you trust it | | User | `~/.o4/skills//SKILL.md` | In every workspace | | Plugin | The plugin's `skills` folder, or the folders its Codex, Claude Code or Cursor manifest lists under `skills` | Wherever the plugin is installed | | Built-in | Inside o4 | Always, through the model's `skill` tool | When two skills have the same name, a project skill wins over a user skill, a user skill wins over a plugin skill, and a plugin skill wins over a built-in one. o4 ignores a project's `.o4/skills` folder until you trust the workspace, so a repository you just cloned can't add instructions to your sessions. See [Workspace trust](/safety/workspace-trust). To install skills that others have written, install a plugin that contains them. o4 calls these plugins skill packs. See [Plugins and marketplaces](/extend/plugins). ### Built-in skills o4 ships with five skills that the model can load: | Name | What it covers | | - | - | | `commit` | Safely inspect, stage, commit, and verify requested git changes | | `pull-request` | Inspect a branch and create a GitHub pull request with an accurate summary and test plan | | `verification` | Choose proportionate tests and checks, then report verification evidence accurately | | `security-review` | Review changed code for concrete authorization, injection, secret, supply-chain, and boundary risks | | `delegation` | Delegate bounded work to subagents with explicit contracts and independently verify the results | Built-in skills don't appear in `/skills` and don't have slash commands. To change how one works, create a project or user skill with the same name. ## The SKILL.md format A `SKILL.md` file is Markdown with optional YAML front matter between `---` lines. A skill must be a regular file, not a symlink, and at most 1 MiB. ```markdown theme={null} --- description: One line that tells the model when this skill applies. context: fork disable-model-invocation: false --- The instructions go here. ``` What the model sees when it lists or searches skills. Write it so the model can tell when the skill applies. Without it, o4 uses the first non-empty line of the body, without any leading `#`. The model sees at most 200 characters. For project and user skills, `/skills` and the slash command menu always show the body's first line instead. Set to `fork` to hand the skill to a subagent when you invoke it as a slash command. o4 shows "Running `` in background..." and sends the model the skill's text with a request to run it as a subagent; the model then starts one with its `agent` tool. See [Subagents](/guides/subagents). Shown in the skill's details in `/skills`. For project and user skills it doesn't limit which tools the model can use. In a plugin's skill, a tool that isn't in the plugin's `permissions.tools` keeps the skill from loading. See [Plugins and marketplaces](/extend/plugins). Shown in the skill's details in `/skills`. o4 doesn't switch models for the skill. Hooks that run only while the skill runs. Each has an `event`, an optional `matcher` and a `command`. See [Hooks in skills](/extend/hooks#hooks-in-skills). When `true`, running the skill as a slash command shows its text in o4 without sending it to the model. Use it for checklists and reference notes you want to read yourself. A project or user skill's name always comes from its folder name; a `name` field in the front matter doesn't change it. In a plugin's skill, a `name` field sets the slash command name and the name in `/skills`, but the model's `skill` tool still uses the folder name. Keep the two the same. ### Arguments When you run a skill as a slash command, o4 replaces every `$ARGUMENTS` in the body with the text you typed after the command. If you type nothing, `$ARGUMENTS` becomes an empty string. In a plugin's skill, o4 also replaces `$CWD` with the working directory and `$O4_PLUGIN_ROOT` with the plugin's folder. When the model loads a skill with its `skill` tool, it gets the body without any replacements. ### Shell commands in skills o4 never runs a line in the body that starts with `!`. When you run a project or user skill as a slash command, o4 replaces each such line with a note like this before the model sees it: ```text theme={null} [Embedded skill command disabled; run through Bash approval: git status] ``` When the model loads a skill with its `skill` tool, or you run a plugin's skill, the line reaches the model as written, and still isn't run. If a skill needs a command's output, tell the model to run the command. It then goes through the normal approval, sandbox, and hook checks. ## How the model uses skills The model has a `skill` tool with three uses: * With no arguments, it lists the available skills with their names, where each comes from, and their descriptions. It shows up to 50. * With `query`, it searches skill names and descriptions. * With `name`, it loads that skill's full instructions. Skill text isn't added to the model's context until the model loads a skill, so having many skills costs little. The `skill` tool never asks for approval, because it only reads instructions. A clear `description` is what lets the model find the right skill. ## Run a skill yourself Type `/` and the skill's name, followed by any arguments: ```text theme={null} /release-notes since v2.3.0 ``` o4 loads the skill, fills in `$ARGUMENTS`, and sends it to the model as your next message. Built-in slash commands take precedence, so a skill named `help` can't replace `/help`. Skills from plugins run the same way. ## Manage skills with /skills `/skills` opens the skill browser. Its tabs are **All**, **Project**, **User**, **Plugin**, and **Errors**. The **Errors** tab lists skills that failed to load, such as a `SKILL.md` with invalid front matter, and notes when project skills were skipped because the workspace isn't trusted. Select a skill to see its details and act on it: * **Select skill** puts `/` in the prompt so you can add arguments. * **Edit skill** opens the `SKILL.md` in your editor. * **Delete skill** removes it. * **View definition** shows the skill's description and where it comes from. In o4 0.2.74, selecting it does nothing more. A skill that [Project Scout](/guides/code-intelligence) turned off has **Enable skill** instead of **Select skill**. It removes the skill from `disabled_skills` in the project's `.o4/config.toml`. While a skill is turned off, it's left out of the slash command menu, and running it only shows "Skill '``' is disabled by Project Scout." The model can still load it with its `skill` tool. You can't edit or delete plugin skills from the browser. Change or remove the plugin instead. While the model is working, you can still open the browser, select a skill, and use **Enable skill**, but creating, editing or deleting a skill is refused: o4 closes the browser and shows `Wait for the current turn to finish before making this change.` You can also jump straight to an action: | Command | What it does | | - | - | | `/skills create [name]` | Start creating a skill, with this name filled in if you give one | | `/skills select ` | Open the skill's details | | `/skills edit ` | Open the skill's details with **Edit skill** selected | | `/skills delete ` | Open the skill's details with **Delete skill** selected | The **Skills** tab in `/config` (run `/config skills` to go straight to it) has two rows: * **Open skill browser** opens the same skill browser as `/skills`. * **Install skill packs** opens the plugin browser, the same as `/plugins`, where you can find and install plugins that bundle skills. See [Plugins and marketplaces](/extend/plugins).