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YAML Composer

Build an entire multi-agent setup from a single YAML file. 
pip install orxhestra[composer]

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Minimal example

defaults:
  model:
    provider: openai
    name: gpt-5.4

agents:
  assistant:
    type: llm
    instructions: "You are a helpful assistant."

main_agent: assistant

from orxhestra.composer import Composer

agent = Composer.from_yaml("orx.yaml")
async for event in agent.astream("Hello"):
    print(event.text)

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Named models

models:
  smart:
    provider: anthropic
    name: claude-opus-4-6
    max_tokens: 8192
  fast:
    provider: openai
    name: gpt-5.4-mini

agents:
  researcher:
    type: llm
    model: smart
  writer:
    type: llm
    model: fast
Extra keys on a model config are forwarded directly to the LangChain model constructor.

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Tools

tools:
  search:
    function: "myapp.tools.search_web"
  weather:
    mcp:
      url: "http://localhost:8001/mcp"
  exit:
    builtin: "exit_loop"

agents:
  agent:
    type: llm
    tools:
      - search
      - weather
      - function: "myapp.tools.inline_tool"  # inline tool def

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Agent types

  • llm — LlmAgent
  • react — ReActAgent
  • sequential — SequentialAgent (runs agents in order)
  • parallel — ParallelAgent (runs agents concurrently)
  • loop — LoopAgent (repeats until exit_loop or max_iterations)
  • a2a — A2AAgent (remote agent via A2A protocol)

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Multi-agent with transfer

agents:
  triage:
    type: llm
    instructions: "Route to the right specialist."
    tools:
      - transfer:
          targets: [sales, support]
  sales:
    type: llm
    instructions: "Handle sales inquiries."
  support:
    type: llm
    instructions: "Handle support tickets."

main_agent: triage

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Sequential pipeline

agents:
  researcher:
    type: llm
    tools: [search]
  writer:
    type: llm
  pipeline:
    type: sequential
    agents: [researcher, writer]

main_agent: pipeline

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Runner and Server

runner:
  app_name: "my-app"
  session_service: "memory"

server:
  app_name: "my-app"
  version: "1.0.0"
  url: "http://localhost:8000"
  skills:
    - id: qa
      name: Q&A
      description: "Answers questions"

runner = Composer.runner_from_yaml("orx.yaml")
app = Composer.server_from_yaml("orx.yaml")  # FastAPI app