Good catch on the AttributeError. Two small nits before this lands:

1. Missing "id": null per JSON-RPC 2.0 §5.1

Other error branches in handle_request include "id": req_id (tool errors, unknown method). Spec says: "If there was an error in detecting the id in the Request object ... it MUST be Null". Strict clients correlate request-response via id; without it they may ignore the response. Suggested:

return {"jsonrpc": "2.0", "id": None, "error": {"code": -32600, "message": "Invalid Request"}}

2. No regression test

A parametrised test covering None, [], "str", 42, True payloads would lock the fix in. Something like:

@pytest.mark.parametrize("payload", [None, [], "plain", 42, True])
def test_handle_request_invalid_payload_returns_jsonrpc_error(payload):
    resp = handle_request(payload)
    assert resp == {"jsonrpc": "2.0", "id": None, "error": {"code": -32600, "message": "Invalid Request"}}

Otherwise a narrow fix on a real bug.

@mvalentsev faced the issue when agent just refused to send a proper request.

Mitigated this by adding test_tools_call_missing_params and the corresponding fix.
So there was a gap at defense layers. Now:

1. The previous test (-32600 Invalid Request) ensures the entire payload is a valid JSON dictionary before routing.
2. This new test (-32602 Invalid params) ensures that once the request reaches tools/call, it explicitly contains the mandatory params object and name field, preventing an AttributeError crash on the server end.