Nullstone Skills Catalog
A skill is a package of instructions (plus optional examples and reference material) that teaches an AI agent how to perform a specific workflow. When a user's prompt matches the skill's trigger description, the agent loads the skill body and follows it.
The Nullstone skills catalog lives at github.com/nullstone-io/agent-skills. Each skill follows the Agent Skills open standard — a self-contained directory with a SKILL.md (name + description frontmatter, markdown body, optional references/ and scripts/). Because the format is a shared standard, the same skill works unmodified in every tool that supports it: Claude Code, OpenAI Codex, Cursor, Gemini CLI, and ~30 others. Drop the directory where your tool reads skills (for Claude Code, ~/.claude/skills/) and it's discovered automatically.
Skills vs MCP tools
They complement each other:
| Surface | Analogy | Example |
|---|---|---|
| MCP tools | Verbs — things the agent can do. | modules_find returns a list of postgres modules. |
| Skills | Conventions — how the agent should use the verbs. | nullstone-config-files says: "look up the module's category via modules_describe, then place it under the matching top-level key, using the map form for capabilities." |
Without a skill, an agent can still call MCP tools — but it won't know (for example) that capabilities should use the map form, or that .nullstone/previews.yml is an overlay that should only include diffs from the base. Skills encode those rules so the agent produces consistent, idiomatic output across teams.
Catalog contents
Current skills:
nullstone-config-files— teaches Claude to produce schema-valid, stylistically-consistent.nullstone/*.ymlfiles.
More skills on the way — watch the catalog repo.
Versioning and compatibility
The catalog uses SemVer. A MINOR bump signals a style-rule change that will produce visibly different agent output; a MAJOR bump means previously valid output may become wrong. Read the CHANGELOG before upgrading.
Every skill's reference page on this site pins a catalog version so you know which rules apply.