ADK Integration

Litestar MCP can be consumed by Google's Agent Development Kit (ADK) as a remote Streamable HTTP MCP server. The integration allows your ADK-based agent applications to discover and invoke tools, as well as read resources exposed by your Litestar application.

Note

Google ADK is an optional client integration. The google-adk package is not installed as a runtime dependency of litestar-mcp.

Installation

For ADK application users, install google-adk in your client environment:

pip install google-adk

For contributors running the compatibility test harness:

uv sync --group test --group adk
uv run pytest -m adk tests/integration/test_google_adk_mcp_toolset.py

Connecting from an ADK Agent

Google ADK connects to remote MCP servers using McpToolset combined with StreamableHTTPConnectionParams.

Remote Connection Snippet

Here is how to set up the toolset connection in your ADK agent application:

docs/examples/snippets/adk_snippets.py

def connect_simple() -> "McpToolset":
    """Connect to the Litestar MCP server without authentication."""
    toolset = McpToolset(
        connection_params=StreamableHTTPConnectionParams(
            url="https://api.example.com/mcp",
            headers={"Accept": "application/json, text/event-stream"},
        )
    )
    return toolset

Authentication Headers

If your Litestar MCP server uses bearer authentication (see Authentication), pass the authorization headers in StreamableHTTPConnectionParams:

docs/examples/snippets/adk_snippets.py

def connect_with_auth() -> "McpToolset":
    """Connect to the Litestar MCP server with bearer token authentication."""
    toolset = McpToolset(
        connection_params=StreamableHTTPConnectionParams(
            url="https://api.example.com/mcp",
            headers={
                "Authorization": "Bearer <your_valid_token>",
                "Accept": "application/json, text/event-stream",
            },
        )
    )
    return toolset

Cleanup

MCP requests are stateless, but ADK's HTTP client still owns network connections. Close the toolset during application shutdown:

docs/examples/snippets/adk_snippets.py

async def run_and_cleanup(toolset: "McpToolset") -> "None":
    """Clean up and close the toolset connection."""
    await toolset.close()

Compatibility Matrix

Google ADK 2.3 still implements the initialize-era lifecycle and therefore cannot connect to the modern-only 2026-07-28 endpoint. The table records the compatibility boundary until ADK adds the stateless lifecycle:

Feature	Supported in ADK	Verification Path / Note
Tool Discovery	No	ADK sends the removed initialize request
Tool Execution	No	Blocked by the lifecycle mismatch
Auth Propagation	No	Header propagation works, but initialization is rejected
Resource Listing	No	Blocked by the lifecycle mismatch
Resource Reading	No	Blocked by the lifecycle mismatch
Resource Templates	No (Direct MCP)	Covered by direct MCP tests (tests/integration/test_resources_templates.py)
Completion	No (Direct MCP)	Covered by direct MCP tests (tests/integration/test_resources_templates.py)
Subscriptions	No (Direct MCP)	Covered by direct MCP tests (tests/unit/test_subscriptions.py)
Tasks Extension	No (Direct MCP)	Covered by direct MCP tests (tests/unit/test_tasks.py)

MCP vs A2A Protocol Boundary

The plugin's separate /.well-known/agent-card.json document is not MCP discovery and does not imply an A2A execution endpoint. MCP clients must call server/discover.

Full Agent-to-Agent (A2A) protocol compatibility requires: - A separate A2A routing tree. - A dedicated A2A agent card endpoint. - Skill execution pipelines aligned with the A2A spec.

Treating A2A as distinct from MCP prevents client-side handshake confusion.

Production Persistence Hardening

For high-availability or multi-replica production deployments of ADK and Litestar MCP:

• MCP request processing itself needs no sticky routing.

• Configure Tasks with a shared Litestar Store when task handles must survive process restarts or move between replicas.

• Configure subscription_channels with a shared Channels backend when notifications must fan out across workers. Subscription streams have no replay.