Swarm
FrameworkFreeOpenAI's experimental multi-agent orchestration framework.
Capabilities12 decomposed
stateless multi-agent orchestration with handoff routing
Medium confidenceImplements a lightweight run loop (Swarm.run() in core.py) that coordinates multiple agents by detecting when a tool call returns an Agent object, automatically switching execution context without persisting state to external servers. Unlike the Assistants API, all conversation history and context variables remain client-side, enabling full control over agent transitions and state mutations through Python function returns.
Uses Python function return values as the handoff mechanism (isinstance(result.value, Agent) check in core.py line 276) rather than explicit routing tables or configuration, making agent transitions first-class language constructs that are testable and debuggable as normal Python code.
Simpler and more testable than Assistants API for multi-agent flows because state stays client-side and handoffs are explicit function returns, not opaque server-side thread transfers.
automatic python-to-json-schema function conversion with signature inspection
Medium confidenceConverts Python functions into OpenAI-compatible JSON schemas via function_to_json() utility (swarm/util.py lines 31-87) using inspect module to extract parameter names, type hints, and docstrings. Automatically detects which functions require context_variables by inspecting function signatures, enabling dynamic injection of shared state without explicit parameter passing in tool definitions.
Detects context_variables requirement via inspect.signature() and automatically injects the dict into function calls without requiring explicit parameter declaration in the tool schema, reducing boilerplate while maintaining type safety through Python's native function signatures.
More Pythonic than manual schema definition (vs LangChain's @tool decorator approach) because it leverages native Python introspection; less verbose than Anthropic's tool_use pattern which requires explicit parameter mapping.
repl-based interactive agent testing and demonstration
Medium confidenceSwarm includes a REPL loop (referenced in architectural overview) that allows interactive testing of agents by accepting user input, running agents, and displaying responses in a command-line interface. The REPL maintains conversation history across turns and supports agent switching, enabling rapid exploration of multi-agent behavior without writing test code.
REPL is built into the Swarm repository as a demo loop, not a separate tool; it uses the same Swarm.run() API as production code, ensuring that interactive behavior matches programmatic behavior.
More integrated than external chat interfaces (vs Gradio or Streamlit) because it's part of the framework; simpler than full IDE integration because it's just a Python loop reading stdin.
airline customer service example with specialized agent routing
Medium confidenceSwarm includes a complete airline customer service example (referenced in Examples section) that demonstrates multi-agent patterns: a triage agent routes customers to specialized agents (rebooking, refunds, general support) based on issue type. Each agent has specific instructions and tools, and handoffs are implemented as function returns, showing how to structure real-world multi-agent applications.
Example is a complete, runnable application (not just code snippets) that demonstrates the full Swarm lifecycle: agent creation, tool definition, handoff logic, and conversation management in a realistic domain.
More comprehensive than isolated code examples (vs scattered snippets) and more realistic than toy examples because it shows multi-agent routing and tool integration together.
dynamic instruction generation with callable-based context awareness
Medium confidenceAllows Agent instructions to be either static strings or callables that receive context_variables and return instruction strings at runtime (swarm/core.py lines 159-161). This enables instruction content to adapt based on conversation state, user metadata, or external data without re-creating Agent objects, implementing a lightweight form of dynamic prompting.
Instructions are first-class callables in the Agent type definition, allowing instruction logic to be versioned, tested, and swapped as Python functions rather than embedded in prompt strings, enabling programmatic instruction composition and A/B testing.
More flexible than static system prompts (vs basic LLM APIs) and simpler than full prompt template engines (vs Langchain's PromptTemplate) because it's just Python functions with access to context_variables.
tool call execution with result wrapping and context mutation
Medium confidenceExecutes tool functions returned by the LLM and wraps results in a Result object (swarm/types.py lines 11-15) that can optionally include updated context_variables. The run loop (core.py lines 250-264) detects Result objects and merges context updates back into the shared state dict, enabling functions to mutate agent context without side effects or global state.
Uses a lightweight Result type (not a full state machine) to couple return values with context mutations, allowing tools to be pure functions that explicitly declare state changes rather than relying on closures or global state, making execution flow traceable and testable.
Simpler than LangChain's AgentAction/AgentFinish pattern because Result is just a dataclass, not part of a larger action/observation loop; more explicit than implicit context mutation via function side effects.
streaming-aware message handling with token-level response iteration
Medium confidenceIntegrates with OpenAI's streaming API to yield partial responses token-by-token via get_chat_completion() (core.py line 165), allowing callers to display agent responses in real-time. The run loop accumulates streamed tokens into full messages before processing tool calls, maintaining compatibility with the non-streaming execution path while enabling progressive output rendering.
Streaming is optional and transparent to the agent logic; the same run() method handles both streaming and non-streaming by yielding Response objects, allowing callers to choose rendering strategy without agent code changes.
More integrated than manual streaming wrappers (vs calling OpenAI API directly) because the run loop handles token accumulation and tool call parsing; simpler than LangChain's streaming callbacks because it's just a generator parameter.
agent-aware message history management with role-based filtering
Medium confidenceMaintains a conversation history as a list of dicts with 'role' and 'content' keys, automatically appending user messages and agent responses while filtering out internal tool calls from the LLM's perspective. The run loop (core.py lines 139-229) manages message ordering and ensures tool results are formatted as 'tool' role messages that the LLM can process for subsequent decisions.
Message history is a simple list of dicts passed by reference, allowing callers to inspect, modify, or persist it directly without API abstractions; tool results are formatted as 'tool' role messages that the LLM natively understands, not wrapped in custom structures.
More transparent than Assistants API (which hides message history) and simpler than LangChain's BaseMemory because it's just a Python list that callers fully control.
turn-limited execution with configurable loop termination
Medium confidenceImplements a configurable turn limit in the run loop (core.py line 139) that terminates execution after a maximum number of agent-LLM interactions, preventing infinite loops or runaway tool call chains. The limit is enforced before each API call, allowing graceful termination with the current message history intact for inspection.
Turn limit is a simple counter in the run loop, not a complex timeout or resource manager; termination is clean (returns current state) rather than forceful, allowing callers to inspect partial results and decide next steps.
More straightforward than timeout-based limits (vs wall-clock timeouts) because it's deterministic and testable; simpler than token-based budgets because it doesn't require token counting.
mock client testing infrastructure for deterministic agent validation
Medium confidenceProvides a MockClient class (referenced in Testing section) that replaces the OpenAI API client for unit testing, allowing tests to inject predefined LLM responses without making real API calls. Tests can verify agent behavior, tool call sequences, and state mutations in isolation with full control over LLM outputs.
MockClient is a drop-in replacement for the OpenAI client that integrates with the Swarm run loop, allowing tests to use the exact same agent code as production without API abstraction layers or test-specific code paths.
More integrated than mocking the requests library (vs monkeypatching HTTP) because it works at the Swarm API level; simpler than VCR-based recording because responses are explicit Python objects, not YAML fixtures.
multi-function agent capability registration with optional filtering
Medium confidenceAgents can declare a list of functions they have access to (swarm/types.py Agent.functions field), which are converted to JSON schemas and sent to the LLM as available tools. The LLM can then choose to call any of these functions, and Swarm routes the calls to the correct Python function via name matching and argument unpacking.
Functions are registered as a simple list on the Agent object, not in a separate registry or configuration file; the Swarm framework handles schema generation and routing transparently, making tool management as simple as Python list operations.
More flexible than fixed tool sets (vs monolithic agents) and simpler than plugin systems (vs LangChain's Tool abstraction) because it's just a Python list of functions.
model-aware agent execution with per-agent model selection
Medium confidenceEach Agent can specify a model field (e.g., 'gpt-4', 'gpt-3.5-turbo') that determines which OpenAI model is used for that agent's completions. The run loop passes the agent's model to get_chat_completion(), enabling multi-model workflows where different agents use different models based on capability or cost requirements.
Model is a field on the Agent type, not a global configuration, enabling per-agent model selection without wrapper layers or routing logic; the run loop simply passes agent.model to the OpenAI client.
More granular than global model configuration (vs single model for all agents) and simpler than LangChain's LLMRouter because it's just a string field on the Agent.
Capabilities are decomposed by AI analysis. Each maps to specific user intents and improves with match feedback.
Related Artifactssharing capabilities
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openclaw-qa
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Web
[Paper - CAMEL: Communicative Agents for “Mind”
Best For
- ✓teams building educational multi-agent systems or prototypes
- ✓developers who need fine-grained control over agent state and transitions
- ✓builders testing agent coordination patterns before production deployment
- ✓Python developers building agents who want to avoid boilerplate schema definitions
- ✓teams that need tight coupling between function implementation and tool availability
- ✓prototypers who value rapid iteration over strict schema validation
- ✓developers prototyping agents and exploring behavior
- ✓demos and presentations showing agent capabilities
Known Limitations
- ⚠No built-in persistence — all state lives in memory; requires manual serialization for durability
- ⚠Stateless design means no automatic recovery from mid-execution failures; caller must implement retry logic
- ⚠Single-threaded execution loop; concurrent agent operations require external orchestration
- ⚠Turn limit enforced in run loop (default behavior) but no built-in timeout management per agent
- ⚠Type hint mapping is basic (str→'string', int→'integer', etc.); complex types like Union or generics may not convert correctly
- ⚠Docstring parsing is simple string extraction; complex NumPy/Google-style docstrings may not parse parameter descriptions accurately
Requirements
Input / Output
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About
OpenAI's experimental educational framework for multi-agent orchestration that demonstrates lightweight patterns for agent handoffs and routines using simple Python abstractions over the Chat Completions API.
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Alternatives to Swarm
OpenAI's managed agent API — persistent assistants with code interpreter, file search, threads.
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