AFPS Specification

AFPS (Agent Format Packaging Standard) is the portable format Appstrate uses to distribute agents, skills, tools, and providers. It is an open specification published under a permissive license, maintained in a separate repository from the Appstrate runtime, and intended to be implementable by other runtimes.

Why a separate format

Models, toolkits, and runtimes are fragmenting fast. MCP covers tool transport. A2A covers agent-to-agent messaging. Anthropic's Agent Skills cover portable instructions. None of them covers what happens between the source and the runtime: versioning, integrity, dependency resolution, multi-tenant distribution, credential isolation at install time.

AFPS fills that gap. It wraps a skill, tool, agent, or provider into a ZIP with a manifest.json that declares the type, version, integrity hash, and optional dependencies. Anything that can parse the manifest and verify the hash can install and run an AFPS package.

We wrote the long-form rationale on the blog: Why we wrote AFPS.

Where the spec lives

The canonical specification, JSON Schema, and governance process are in a dedicated public repository:

github.com/appstrate/afps-spec

The npm package with the TypeScript types and validators is @afps-spec/schema. Appstrate's runtime consumes it directly.

Scope at a glance

The spec defines:

Package types: agent, skill, tool, provider.
Manifest schema: required fields (type, name, version), optional fields (description, dependencies, definition, fileConstraints, uiHints).
Integrity: SHA-256 SRI hashes computed over the ZIP contents.
Versioning rules: semver with forward-only constraints and dist-tag conventions.
Dependency resolution: semver range matching inside a package catalog.
Compatibility with Anthropic Agent Skills: a pure SKILL.md skill folder ZIPped with an AFPS manifest is a valid AFPS package.

License and governance

AFPS is published under CC-BY 4.0. You can implement it, fork it, vendor it, or build a registry around it without asking permission. The governance process accepts proposals from any contributor via issues and pull requests on the spec repo.

Integration with Appstrate

Appstrate's routes under /api/packages/* accept, store, and serve AFPS packages. See:

Build / Packages for the consumer API (importing, pinning, forking).
Extend / Skills for authoring and publishing.

Contributing to the spec

Issues, proposals, and pull requests are welcomed on the spec repo:

github.com/appstrate/afps-spec/issues

The process is designed to absorb real-world feedback, especially from teams running multi-tenant agents in production today.