Content
# MCP-A2A Bridge
> A lightweight Model Context Protocol (MCP) **server** that proxies requests to one or more remote **A2A** agents.
>
> It lets tools that natively speak MCP – such as Claude, Cursor AI, or any other MCP-aware client – interact with agents that expose the [A2A protocol](https://github.com/modelcontextprotocol/a2a).
> In short: **MCP on the front-end, A2A on the back-end.**
---
## Why would I want this?
* **Use your existing AI client as an A2A Client** Use Claude Desktop, Cursor, etc. as a client that can connect to and use A2A servers
---
### MCP config in Claude / Cursor
To integrate with an MCP client that supports local servers (like Claude Desktop or Cursor), configure it to run the bridge using `npx`.
**Example `claude_desktop_config.json`:**
```jsonc
{
"mcpServers": {
"MCP-A2A Bridge": {
"command": "npx",
"args": [
"-y",
"@agentopolis/mcp-a2a-bridge@latest",
"--a2a-server-config-dir=/Users/ryan/.config/mcp-a2a-bridge/servers" // Replace with your desired absolute path
]
}
}
}
```
**Important:**
* Replace `/Users/ryan/.config/mcp-a2a-bridge/servers` with the actual **absolute path** you want to use on your system.
Restart or refresh your application after adding this configuration. The bridge should appear as a new tool provider.
---
## Usage
**Example:**
Send these prompts to your AI client:
1. Add an A2A server using its url
```
add this a2a server: https://a2a-demos.agentopolis.ai/bella-restaurant
```
2. Ask what skills the A2A server has:
```
what skills does Bella have?
```
3. Use the skills
```
What kind of specials are they running?
```
and
```
Make a reservation for two for thursday at 8pm, under the name Ryan
```
## Screenshots using Claude Desktop
1. Adding an A2A server
2. Checking the MCP Tools
4. Asking about specials
5. Making a reservation
6. Listing servers
## Configuration Directory
The bridge stores A2A server registrations as JSON files. The location is determined as follows:
1. `--a2a-server-config-dir=/your/absolute/path` (CLI flag - **Recommended**)
2. `./.mcp-a2a-servers` (Relative to the current working directory of the bridge process – default if the CLI flag is not set. This may be unpredictable when run by other tools.)
A typical entry lives at `<config_dir>/<serverId>.json`.
---
## Available MCP tools
| Tool name | Purpose | Input schema |
|-----------|---------|-------------|
| `a2a_register_server` | Fetches an A2A agent's card from `<url>/.well-known/agent.json` and saves it. | `{ url: string }` |
| `a2a_reload_servers` | Re-reads all JSON files in the config directory. | _none_ |
| `a2a_list_servers` | Lists registered servers. | _none_ |
| `a2a_get_server_details` | Full card for a given server. | `{ serverId: string }` |
| `a2a_remove_server` | Delete a registration. | `{ serverId: string }` |
| `a2a_send_task` | Generic escape hatch – call any A2A agent with an arbitrary message. | `{ serverId: string; taskId: string; message?: string | Message }` |
| _`<serverId>_<skillId>`_ | **Auto-generated**. One tool per skill on every registered agent. Accepts `{ message: string }`. | — |
> A `<serverId>_<skillId>` tool name is slugified (`my-agent` + `provide-restaurant-info` → `my-agent_provide-restaurant-info`).
---
Released under the MIT license.
