A2A MCP Server
Enables Claude to connect and interact with A2A Protocol agents, allowing discovery of agent capabil...
Open the FastMCP connection interface
- Click the "Install Now" button to open the FastMCP / connection UI where environment variables (ENVs) are entered.
Add the required environment variable: A2A_AGENT_CARDS
- In the FastMCP ENVs panel add a variable named
A2A_AGENT_CARDS. - The value must be a JSON-stringified list of objects; each object must include a
urlkey (the full Agent Card URL) and may include an optionalcustom_headersobject for authentication headers. Example value (paste this whole string as the ENV value):[{"url":"https://example.com/.well-known/agent-card.json","custom_headers":{"X-API-Key":"YOUR_API_KEY"}}] - You can include multiple agents by adding multiple objects in the list (comma-separated). (Format is described in the project README.)
- In the FastMCP ENVs panel add a variable named
How to obtain an Agent Card URL
- Option A — Use a public agent: copy the Agent Card URL provided by the agent registry or provider (for example a2anet listings or a demo repository).
- Option B — If you run the agent yourself: the agent must publish its Agent Card JSON at a well-known path such as
https://<your-domain>/.well-known/agent-card.json. Ensure your agent service is reachable at that URL. (a2a-protocol.org)
If the agent requires authentication (API key / token)
- Get the API key or token from the agent provider (their dashboard or account settings).
- Place it inside
custom_headersin theA2A_AGENT_CARDSlist, e.g.[{"url":"https://example.com/.well-known/agent-card.json","custom_headers":{"Authorization":"Bearer YOUR_TOKEN"}}] - Use the exact header name the agent expects (e.g.,
X-API-Key,Authorization).
Verify the Agent Card URL before saving
- From your terminal, run:
- curl:
curl -sS https://example.com/.well-known/agent-card.json - (optional) format with jq:
curl -sS https://example.com/.well-known/agent-card.json | jq .
- curl:
- The returned JSON should contain top-level metadata such as
name,description,url, and askillsarray (this confirms the card is valid). (a2a-protocol.org)
- From your terminal, run:
Paste the JSON value into FastMCP and save
- In the FastMCP ENVs UI (opened from "Install Now"), paste the JSON-stringified list as the value for
A2A_AGENT_CARDS. - Save / Apply the settings in the FastMCP interface.
- In the FastMCP ENVs UI (opened from "Install Now"), paste the JSON-stringified list as the value for
Start or restart the MCP server
- Use the FastMCP UI’s install/start action (or restart the MCP) so the server picks up the new ENV.
- After startup, use the MCP tools
list_available_agentsto confirm the agent(s) are discoverable.
Troubleshooting tips
- If
list_available_agentsfails to show the agent, re-check:- The Agent Card URL is reachable from the host (curl from the host).
- Any
custom_headersare correct and accepted by the agent endpoint. - The Agent Card JSON is valid and contains
skillsandurl. (a2a-protocol.org)
- If
(Optional) Multiple agents
- Provide a list with multiple agent objects in the same
A2A_AGENT_CARDSvalue:[{"url":"https://agent1.example/.well-known/agent-card.json"},{"url":"https://agent2.example/.well-known/agent-card.json","custom_headers":{"X-API-Key":"KEY2"}}] - Save and restart as above.
- Provide a list with multiple agent objects in the same
Done
- Once the env is saved and the MCP restarted, use
list_available_agentsandsend_message_to_agentto interact with the configured agents.
- Once the env is saved and the MCP restarted, use
How to Install A2A MCP Server
Install A2A MCP Server MCP server with one click through FastMCP. Choose your preferred AI development tool below:
Claude Desktop
Click "Claude Desktop" in Quick Start
Cursor IDE
Click "Cursor IDE" in Quick Start
VS Code
Click "VS Code" in Quick Start
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Configuration for
Environment Variables
Please provide values for the following environment variables:
HTTP Headers
Please provide values for the following HTTP headers:
started!
The MCP server should open in . If it doesn't open automatically, please check that you have the application installed.
Copy and run this command in your terminal:
Make sure Gemini CLI is installed:
Visit Gemini CLI documentation for installation instructions.
Make sure Claude Code is installed:
Visit Claude Code documentation for installation instructions.
Installation Steps:
Configuration
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