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chore: a2a agent card docs, refine existing a2a docs

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Greyson LaLonde
2026-01-14 22:46:53 -05:00
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233
docs/en/learn/a2a-agent-delegation.mdx
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@@ -1,43 +1,48 @@
---
title: Agent-to-Agent (A2A) Protocol
description: Enable CrewAI agents to delegate tasks to remote A2A-compliant agents for specialized handling
description: Agents delegate tasks to remote A2A agents and/or operate as A2A-compliant server agents.
icon: network-wired
mode: "wide"
---
## A2A Agent Delegation
CrewAI supports the Agent-to-Agent (A2A) protocol, allowing agents to delegate tasks to remote specialized agents. The agent's LLM automatically decides whether to handle a task directly or delegate to an A2A agent based on the task requirements.
<Note>
A2A delegation requires the `a2a-sdk` package. Install with: `uv add 'crewai[a2a]'` or `pip install 'crewai[a2a]'`
</Note>
CrewAI treats [A2A protocol](https://a2a-protocol.org/latest/) as a first-class delegation primitive, enabling agents to delegate tasks, request information, and collaborate with remote agents, as well as act as A2A-compliant server agents.
In client mode, agents autonomously choose between local execution and remote delegation based on task requirements.
## How It Works
When an agent is configured with A2A capabilities:
1. The LLM analyzes each task
1. The Agent analyzes each task
2. It decides to either:
- Handle the task directly using its own capabilities
- Delegate to a remote A2A agent for specialized handling
3. If delegating, the agent communicates with the remote A2A agent through the protocol
4. Results are returned to the CrewAI workflow
<Note>
A2A delegation requires the `a2a-sdk` package. Install with: `uv add 'crewai[a2a]'` or `pip install 'crewai[a2a]'`
</Note>
## Basic Configuration
<Warning>
`crewai.a2a.config.A2AConfig` is deprecated and will be removed in v2.0.0. Use `A2AClientConfig` for connecting to remote agents and/or `A2AServerConfig` for exposing agents as servers.
</Warning>
Configure an agent for A2A delegation by setting the `a2a` parameter:
```python Code
from crewai import Agent, Crew, Task
from crewai.a2a import A2AConfig
from crewai.a2a import A2AClientConfig
agent = Agent(
role="Research Coordinator",
goal="Coordinate research tasks efficiently",
backstory="Expert at delegating to specialized research agents",
llm="gpt-4o",
a2a=A2AConfig(
a2a=A2AClientConfig(
endpoint="https://example.com/.well-known/agent-card.json",
timeout=120,
max_turns=10
@@ -54,9 +59,9 @@ crew = Crew(agents=[agent], tasks=[task], verbose=True)
result = crew.kickoff()
```
## Configuration Options
## Client Configuration Options
The `A2AConfig` class accepts the following parameters:
The `A2AClientConfig` class accepts the following parameters:
<ParamField path="endpoint" type="str" required>
The A2A agent endpoint URL (typically points to `.well-known/agent-card.json`)
@@ -95,14 +100,30 @@ The `A2AConfig` class accepts the following parameters:
Transport protocol for A2A communication. Options: `JSONRPC` (default), `GRPC`, or `HTTP+JSON`.
</ParamField>
<ParamField path="accepted_output_modes" type="list[str]" default='["application/json"]'>
Media types the client can accept in responses.
</ParamField>
<ParamField path="supported_transports" type="list[str]" default='["JSONRPC"]'>
Ordered list of transport protocols the client supports.
</ParamField>
<ParamField path="use_client_preference" type="bool" default="False">
Whether to prioritize client transport preferences over server.
</ParamField>
<ParamField path="extensions" type="list[str]" default="[]">
Extension URIs the client supports.
</ParamField>
## Authentication
For A2A agents that require authentication, use one of the provided auth schemes:
<Tabs>
<Tab title="Bearer Token">
```python Code
from crewai.a2a import A2AConfig
```python bearer_token_auth.py lines
from crewai.a2a import A2AClientConfig
from crewai.a2a.auth import BearerTokenAuth
agent = Agent(
@@ -110,18 +131,18 @@ agent = Agent(
goal="Coordinate tasks with secured agents",
backstory="Manages secure agent communications",
llm="gpt-4o",
a2a=A2AConfig(
a2a=A2AClientConfig(
endpoint="https://secure-agent.example.com/.well-known/agent-card.json",
auth=BearerTokenAuth(token="your-bearer-token"),
timeout=120
)
)
```
```
</Tab>
<Tab title="API Key">
```python Code
from crewai.a2a import A2AConfig
```python api_key_auth.py lines
from crewai.a2a import A2AClientConfig
from crewai.a2a.auth import APIKeyAuth
agent = Agent(
@@ -129,7 +150,7 @@ agent = Agent(
goal="Coordinate with API-based agents",
backstory="Manages API-authenticated communications",
llm="gpt-4o",
a2a=A2AConfig(
a2a=A2AClientConfig(
endpoint="https://api-agent.example.com/.well-known/agent-card.json",
auth=APIKeyAuth(
api_key="your-api-key",
@@ -139,12 +160,12 @@ agent = Agent(
timeout=120
)
)
```
```
</Tab>
<Tab title="OAuth2">
```python Code
from crewai.a2a import A2AConfig
```python oauth2_auth.py lines
from crewai.a2a import A2AClientConfig
from crewai.a2a.auth import OAuth2ClientCredentials
agent = Agent(
@@ -152,7 +173,7 @@ agent = Agent(
goal="Coordinate with OAuth-secured agents",
backstory="Manages OAuth-authenticated communications",
llm="gpt-4o",
a2a=A2AConfig(
a2a=A2AClientConfig(
endpoint="https://oauth-agent.example.com/.well-known/agent-card.json",
auth=OAuth2ClientCredentials(
token_url="https://auth.example.com/oauth/token",
@@ -163,12 +184,12 @@ agent = Agent(
timeout=120
)
)
```
```
</Tab>
<Tab title="HTTP Basic">
```python Code
from crewai.a2a import A2AConfig
```python http_basic_auth.py lines
from crewai.a2a import A2AClientConfig
from crewai.a2a.auth import HTTPBasicAuth
agent = Agent(
@@ -176,7 +197,7 @@ agent = Agent(
goal="Coordinate with basic auth agents",
backstory="Manages basic authentication communications",
llm="gpt-4o",
a2a=A2AConfig(
a2a=A2AClientConfig(
endpoint="https://basic-agent.example.com/.well-known/agent-card.json",
auth=HTTPBasicAuth(
username="your-username",
@@ -185,7 +206,7 @@ agent = Agent(
timeout=120
)
)
```
```
</Tab>
</Tabs>
@@ -194,7 +215,7 @@ agent = Agent(
Configure multiple A2A agents for delegation by passing a list:
```python Code
from crewai.a2a import A2AConfig
from crewai.a2a import A2AClientConfig
from crewai.a2a.auth import BearerTokenAuth
agent = Agent(
@@ -203,11 +224,11 @@ agent = Agent(
backstory="Expert at delegating to the right specialist",
llm="gpt-4o",
a2a=[
A2AConfig(
A2AClientConfig(
endpoint="https://research.example.com/.well-known/agent-card.json",
timeout=120
),
A2AConfig(
A2AClientConfig(
endpoint="https://data.example.com/.well-known/agent-card.json",
auth=BearerTokenAuth(token="data-token"),
timeout=90
@@ -223,7 +244,7 @@ The LLM will automatically choose which A2A agent to delegate to based on the ta
Control how agent connection failures are handled using the `fail_fast` parameter:
```python Code
from crewai.a2a import A2AConfig
from crewai.a2a import A2AClientConfig
# Fail immediately on connection errors (default)
agent = Agent(
@@ -231,7 +252,7 @@ agent = Agent(
goal="Coordinate research tasks",
backstory="Expert at delegation",
llm="gpt-4o",
a2a=A2AConfig(
a2a=A2AClientConfig(
endpoint="https://research.example.com/.well-known/agent-card.json",
fail_fast=True
)
@@ -244,11 +265,11 @@ agent = Agent(
backstory="Expert at working with available resources",
llm="gpt-4o",
a2a=[
A2AConfig(
A2AClientConfig(
endpoint="https://primary.example.com/.well-known/agent-card.json",
fail_fast=False
),
A2AConfig(
A2AClientConfig(
endpoint="https://backup.example.com/.well-known/agent-card.json",
fail_fast=False
)
@@ -267,8 +288,8 @@ Control how your agent receives task status updates from remote A2A agents:
<Tabs>
<Tab title="Streaming (Default)">
```python Code
from crewai.a2a import A2AConfig
```python streaming_config.py lines
from crewai.a2a import A2AClientConfig
from crewai.a2a.updates import StreamingConfig
agent = Agent(
@@ -276,17 +297,17 @@ agent = Agent(
goal="Coordinate research tasks",
backstory="Expert at delegation",
llm="gpt-4o",
a2a=A2AConfig(
a2a=A2AClientConfig(
endpoint="https://research.example.com/.well-known/agent-card.json",
updates=StreamingConfig()
)
)
```
```
</Tab>
<Tab title="Polling">
```python Code
from crewai.a2a import A2AConfig
```python polling_config.py lines
from crewai.a2a import A2AClientConfig
from crewai.a2a.updates import PollingConfig
agent = Agent(
@@ -294,7 +315,7 @@ agent = Agent(
goal="Coordinate research tasks",
backstory="Expert at delegation",
llm="gpt-4o",
a2a=A2AConfig(
a2a=A2AClientConfig(
endpoint="https://research.example.com/.well-known/agent-card.json",
updates=PollingConfig(
interval=2.0,
@@ -303,12 +324,12 @@ agent = Agent(
)
)
)
```
```
</Tab>
<Tab title="Push Notifications">
```python Code
from crewai.a2a import A2AConfig
```python push_notifications_config.py lines
from crewai.a2a import A2AClientConfig
from crewai.a2a.updates import PushNotificationConfig
agent = Agent(
@@ -316,19 +337,137 @@ agent = Agent(
goal="Coordinate research tasks",
backstory="Expert at delegation",
llm="gpt-4o",
a2a=A2AConfig(
a2a=A2AClientConfig(
endpoint="https://research.example.com/.well-known/agent-card.json",
updates=PushNotificationConfig(
url={base_url}/a2a/callback",
url="{base_url}/a2a/callback",
token="your-validation-token",
timeout=300.0
)
)
)
```
```
</Tab>
</Tabs>
## Exposing Agents as A2A Servers
You can expose your CrewAI agents as A2A-compliant servers, allowing other A2A clients to delegate tasks to them.
### Server Configuration
Add an `A2AServerConfig` to your agent to enable server capabilities:
```python a2a_server_agent.py lines
from crewai import Agent
from crewai.a2a import A2AServerConfig
agent = Agent(
role="Data Analyst",
goal="Analyze datasets and provide insights",
backstory="Expert data scientist with statistical analysis skills",
llm="gpt-4o",
a2a=A2AServerConfig(url="https://your-server.com")
)
```
### Server Configuration Options
<ParamField path="name" type="str" default="None">
Human-readable name for the agent. Defaults to the agent's role if not provided.
</ParamField>
<ParamField path="description" type="str" default="None">
Human-readable description. Defaults to the agent's goal and backstory if not provided.
</ParamField>
<ParamField path="version" type="str" default="1.0.0">
Version string for the agent card.
</ParamField>
<ParamField path="skills" type="list[AgentSkill]" default="[]">
List of agent skills. Auto-generated from agent tools if not provided.
</ParamField>
<ParamField path="capabilities" type="AgentCapabilities" default="AgentCapabilities(streaming=True, push_notifications=False)">
Declaration of optional capabilities supported by the agent.
</ParamField>
<ParamField path="default_input_modes" type="list[str]" default='["text/plain", "application/json"]'>
Supported input MIME types.
</ParamField>
<ParamField path="default_output_modes" type="list[str]" default='["text/plain", "application/json"]'>
Supported output MIME types.
</ParamField>
<ParamField path="url" type="str" default="None">
Preferred endpoint URL. If set, overrides the URL passed to `to_agent_card()`.
</ParamField>
<ParamField path="preferred_transport" type="Literal['JSONRPC', 'GRPC', 'HTTP+JSON']" default="JSONRPC">
Transport protocol for the preferred endpoint.
</ParamField>
<ParamField path="protocol_version" type="str" default="0.3">
A2A protocol version this agent supports.
</ParamField>
<ParamField path="provider" type="AgentProvider" default="None">
Information about the agent's service provider.
</ParamField>
<ParamField path="documentation_url" type="str" default="None">
URL to the agent's documentation.
</ParamField>
<ParamField path="icon_url" type="str" default="None">
URL to an icon for the agent.
</ParamField>
<ParamField path="additional_interfaces" type="list[AgentInterface]" default="[]">
Additional supported interfaces (transport and URL combinations).
</ParamField>
<ParamField path="security" type="list[dict[str, list[str]]]" default="[]">
Security requirement objects for all agent interactions.
</ParamField>
<ParamField path="security_schemes" type="dict[str, SecurityScheme]" default="{}">
Security schemes available to authorize requests.
</ParamField>
<ParamField path="supports_authenticated_extended_card" type="bool" default="False">
Whether agent provides extended card to authenticated users.
</ParamField>
<ParamField path="signatures" type="list[AgentCardSignature]" default="[]">
JSON Web Signatures for the AgentCard.
</ParamField>
### Combined Client and Server
An agent can act as both client and server by providing both configurations:
```python Code
from crewai import Agent
from crewai.a2a import A2AClientConfig, A2AServerConfig
agent = Agent(
role="Research Coordinator",
goal="Coordinate research and serve analysis requests",
backstory="Expert at delegation and analysis",
llm="gpt-4o",
a2a=[
A2AClientConfig(
endpoint="https://specialist.example.com/.well-known/agent-card.json",
timeout=120
),
A2AServerConfig(url="https://your-server.com")
]
)
```
## Best Practices
<CardGroup cols={2}>

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lib/crewai/src/crewai/a2a/__init__.py
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@@ -1,8 +1,10 @@
"""Agent-to-Agent (A2A) protocol communication module for CrewAI."""
from crewai.a2a.config import A2AConfig
from crewai.a2a.config import A2AClientConfig, A2AConfig, A2AServerConfig
__all__ = [
"A2AClientConfig",
"A2AConfig",
"A2AServerConfig",
]