Open standard for declarative AI agents — a portable, interoperable schema for defining agents, tools (MCP), and agent-to-agent services (A2A) across runtimes.

Agent Formation defines a vendor-neutral, declarative configuration standard for AI agents and multi-agent systems. The goal is simple:

• Write agent systems once
• Run them anywhere
• Validate them consistently

The standard provides a clear separation between:

• Definition (standard) — how formations, agents, tools, and services are declared
• Implementation (runtimes) — how those declarations are executed by a specific platform

MUXI uses Agent Formation as a reference implementation, but any runtime or framework can adopt this standard.

Agent configurations today are fragmented across frameworks and often tightly coupled to a specific runtime. Agent Formation standardizes the missing layer:

• Portable agent definitions
• Composable multi-agent setups
• Consistent validation and backward compatibility
• Explicit extension points for vendors

Think of Agent Formation as infrastructure-as-code for agents.

Agent Formation supports two file extensions:

• .afs — Agent Formation Schema (recommended)
• .yaml — Standard YAML extension

Both are fully supported and functionally identical. Use .afs for clarity in projects with multiple YAML files.

.
├── schemas/                  # Canonical Formation schemas and templates
│   ├── SCHEMA_GUIDE.md       # Authoritative field reference
│   ├── formation.afs         # Core Formation template
│   ├── agents/               # Agent templates
│   │   ├── minimal.afs
│   │   └── full.afs
│   ├── skills/               # Agent skills (SKILL.md + scripts)
│   │   └── example-skill/
│   ├── mcp/                  # MCP tool server templates
│   │   ├── local_tools.afs
│   │   └── web_tools.afs
│   ├── a2a/                  # Agent-to-agent service templates
│   │   ├── analytics_engine.afs
│   │   └── external_billing_service.afs
│   └── knowledge/            # Knowledge base files directory
│       └── README.md
├── specs/                    # Specification documents
│   ├── formation.md          # Core standard
│   ├── versioning.md         # Versioning policy
│   └── secrets.md            # Secrets specification
├── CHARTER.md
├── CODE_OF_CONDUCT.md
├── GOVERNANCE.md
├── MAINTAINERS.md
├── ROADMAP.md
└── SECURITY.md

Formation files describe complete agent systems with modular components:

• Formation configuration (formation.afs or formation.yaml) Core system settings, LLM models, memory, MCP, A2A, auth, defaults.

• Agent definitions (agents/*.afs) Individual agents with roles, goals, tools, memory, and overrides.

• MCP tool servers (mcp/*.afs) Model Context Protocol servers providing tools/functions.

• A2A services (a2a/*.afs) Agent-to-agent services and external service adapters.

• Skills (skills/) Reusable agent capabilities following the Agent Skills specification. Each skill contains a SKILL.md with instructions, plus optional scripts and assets.

• Knowledge (knowledge/) Portable knowledge assets.

schemas/SCHEMA_GUIDE.md is the authoritative field reference:

• Field-by-field reference
• Override rules and precedence
• Validation rules and examples
• Best practices

cp -r schemas my-formation
cd my-formation

nano formation.afs

# secrets are optional, but recommended for production
# (commands below use MUXI CLI as reference implementation)
muxi secrets init
muxi secrets set OPENAI_API_KEY "your-key"

muxi deploy

muxi validate formation.afs [--schema formation]
muxi validate agents/my-agent.afs --schema agent
muxi validate mcp/my-tools.afs --schema mcp

cp schemas/agents/minimal.afs agents/my-agent.afs
cp schemas/mcp/web_tools.afs mcp/my-tools.afs
cp schemas/a2a/analytics_engine.afs a2a/my-service.afs

1. Declarative first — configuration describes intent, not execution.
2. Portability — configs are runtime-agnostic by default.
3. Presence implies enablement — sections activate features automatically.
4. Sensible defaults — reduce boilerplate for common setups.
5. Backward compatibility — no breaking changes within a major version.
6. Explicit extensibility — vendors add fields via namespaced extensions.

All files include semantic schema versions:

schema: "1.0.0"

• Patch: bugfixes or clarifications
• Minor: backward-compatible additions
• Major: breaking changes with migration tooling

See specs/versioning.md.

This repo defines the Agent Formation Standard. Contributions should include:

1. Schema updates
2. Guide updates
3. Template updates
4. Fixtures and validation coverage
5. Compatibility checks

See CONTRIBUTING.md.

Agent Formation was originally developed as part of the MUXI Stack and contributed to establish a vendor-neutral standard for declarative AI agent systems. MUXI continues to serve as the reference implementation.

Apache License 2.0. See LICENSE.

• MUXI Stack — reference implementation of Agent Formation.

Other implementations are welcome.