Blocks, explained
An interactive guide to every block in Skill Builder: what each one is for and when another fits better, the markdown it writes for SKILL.md, agent files and AGENTS.md, and the checks it gets. Try the fields live; nothing is saved. The interactive version needs JavaScript.
Structure
- Callout
One note, tip or warning that must stand out from the text around it. - Divider
A visual break between two unrelated parts of a long file. - Heading
A section heading on its own, for example above a few reference blocks. - Project overview
The first block of AGENTS.md: what the project is and who it is for. - Project structure
Where things live, so the AI finds the right files first. - Role
The agent's identity, expertise and mission. - Tech stack
Languages, frameworks and main libraries, with the versions that matter. - Title & overview
The first block of a skill or agent: its name as a heading and what it is for.
Instructions
- Arguments
What the text after /name means, for skills people start themselves. - Commands
The exact commands to install, run, build, test and lint, so the AI can check its work. - Gather context first
Files to read and commands to run before the work starts. - Git and pull requests
Branches, commit messages and what a pull request needs. - Output format
Exactly what to produce or hand back, and in what shape. - Principles
A few guiding ideas, each with a short reason, where judgment matters more than steps. - Responsibilities
What the agent owns, so it does not drift into other work. - Step-by-step process
An ordered procedure to follow. Not for conditions, links or rules. - Testing
How tests are written and run, and what must pass before a change is done. - When to use
When this skill or agent should be used (triggers) and when not to.
Examples
- Code snippet
A piece of code to copy or follow exactly, with its language. - Example
Show one input and the output you expect. Examples teach format faster than rules.
Constraints
- Anti-patterns
Mistakes the AI tends to make here, so it avoids them. - Architecture rules
Decisions the AI must respect, such as layers and where logic goes. - Boundaries
What the agent always does, asks about first, and never does. - Boundaries
What every AI tool always does, asks about first, and never does in this project. - Checklist
Things to check before finishing. - Code style
Naming, formatting and patterns a linter does not already enforce. - Completion goal
Work that repeats (fix, check, fix again): the goal, the check, the limit and what happens next. - Definition of done
What has to be true before the whole task is finished, and how to check it. - Path rules
Point Codex and other AI tools at each path rule and its files. Lists the project's rules. - Rules
Constraints and conventions that always apply. - Security
Secrets, personal data and anything that must never leave the project.
Tools
- Agent reference
Hand work off to another agent of the project, and say when. - Bundled resources
List the scripts and files shipped with the skill, and whether to run or read each. - References
Links to outside documentation or files the AI can load when it needs them. - Repository skills and agents
Skills and agents installed in the repository itself, and when to use each. - Resource link
Tell the skill when to read one of its own files (references/, scripts/, …). - Skill Builder (Connect AI)
Tell AI tools to load skills and agents from Skill Builder when they are not installed. - Skill reference
Make this agent or skill use another skill of the project, and say when. It also links the skill. - Skills and agents
List this project's skills and agents with when to use each. It stays up to date. - Tool guidance
How and when the agent uses each tool.
Custom
- Custom markdown
Last resort: only for content that no other block fits.