afd-spec
Agent Flow Definition (AFD)
AFD is an open specification for declaring portable AI workflow packages. It standardizes how flows, skills, extensions, and providers are described, versioned, and distributed. It focuses on package definition and composition, not on tool calling or agent-to-agent transport.
Ecosystem Positioning
MCP -> which tools an agent can use (agent <-> tools)
A2A -> which agents can talk to each other (agent <-> agent)
AFD -> what a workflow package is and how it is declared
(flow definition, dependencies, schemas, execution metadata)
Repository Contents
- spec.md - the AFD v1.0 draft specification
- examples/ - minimal and full package examples
- schema/ - JSON Schema files (generated in
@appstrate/core, see schema/README) - GOVERNANCE.md - change process and stewardship
- CHANGELOG.md - specification history
Scope
AFD defines:
- Package identity with scoped names and semantic versions
- Manifest fields for
flow,skill,extension, andprovider - Registry dependencies and provider configuration
- A constrained schema system for input, output, and config
- ZIP package structure for distribution
AFD does not define:
- Agent runtime APIs
- Prompt execution semantics
- Tool invocation transport
- Agent-to-agent messaging
Relation to Appstrate
AFD was created by Appstrate and published as an independent open specification. The Appstrate core and registry codebases currently act as the reference implementation from which this draft was extracted.
Implementations
| Implementation | Language | Description |
|---|---|---|
@appstrate/core |
TypeScript / Zod 4 | Reference implementation — manifest validation, ZIP parsing, dependency extraction |
The JSON Schema files in schema/ are generated from the Zod definitions in @appstrate/core and included in this repository for self-contained reference.
Contributing
See GOVERNANCE.md for the change process. To propose a normative or editorial change, open an issue using the spec change template.