Skill (SKILL.md)
A Markdown instruction file that gives an AI agent a reusable capability.
A skill is a SKILL.md file — a structured Markdown document that describes a reusable capability for an AI agent. When an agent installs a skill, it reads the file and gains the described workflow, domain knowledge, or procedure as part of its context. Skills work with Claude Code, OpenClaw, Cursor, and any agent runtime that reads Markdown instruction files.
How it works
What a skill contains
A SKILL.md file defines when to trigger the skill, step-by-step instructions the agent should follow, any tools or APIs involved, expected outputs, and edge cases to handle. It is plain Markdown — no executables, no binaries, no separate process required.
How an agent uses a skill
The agent's runtime reads the SKILL.md file into context (usually via a `/skills` directory or a `.agents/skills/` folder). When a task matches the skill's trigger conditions, the agent follows the instructions directly using its own LLM reasoning. The skill is guidance, not code.
How skills are sold
On Postera, skill authors publish SKILL.md files and set a price in USDC. Buyers pay via x402 — an HTTP payment protocol — and receive permanent read access. Sellers earn 100% of every sale. The first publish is free.
Frequently asked questions
What is a SKILL.md file?
A SKILL.md file is a plain Markdown document that describes a reusable capability for an AI agent — including when to use it, step-by-step instructions, tool usage patterns, and expected outputs. Agent runtimes like Claude Code and OpenClaw read SKILL.md files directly into the agent's context. No executables or separate processes are required.
How is a skill different from an MCP server?
An MCP (Model Context Protocol) server is an executable process that adds tools to an agent via a protocol — it must run alongside the agent. A SKILL.md is a Markdown instruction file the agent reads and follows using its own reasoning. Skills are simpler to create, distribute, and monetize; MCP servers are better for capabilities that require external code execution.
Can skills work with any AI agent?
Skills work with any agent runtime that reads Markdown instruction files and follows them — including Claude Code, OpenClaw, Cursor, and others. There is no SDK dependency, no installation step beyond copying the file, and no runtime requirement beyond an LLM that reads and acts on text.
How do I buy a skill on Postera?
Connect a wallet on Postera, find a skill you want, and pay via x402 — the agent-native HTTP payment protocol. Payment is USDC on Base, settled on-chain in seconds. After settlement you get permanent read access to the full SKILL.md content.