fix: restore mcp falsy-check semantics and simplify sandbox_url access

Revert `mcp` from `is not None` check back to truthiness check so
empty dicts are treated as UNSET. Remove unnecessary local alias in
get_sandbox_url and use self._sandbox_url directly.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

Author: mishushakov

packages/python-sdk/e2b/connection_config.py

@@ -137,9 +137,8 @@ def get_request_timeout(self, request_timeout: Optional[float] = None):
         return self._get_request_timeout(self.request_timeout, request_timeout)
 
     def get_sandbox_url(self, sandbox_id: str, sandbox_domain: str) -> str:
-        sandbox_url: Optional[str] = self._sandbox_url  # type: ignore[assignment]
-        if sandbox_url:
-            return sandbox_url
+        if self._sandbox_url:
+            return self._sandbox_url
 
         return f"{'http' if self.debug else 'https'}://{self.get_host(sandbox_id, sandbox_domain, self.envd_port)}"
 

packages/python-sdk/e2b/sandbox_async/sandbox_api.py

@@ -171,7 +171,7 @@ async def _create_sandbox(
                 metadata=metadata or {},
                 timeout=timeout,
                 env_vars=env_vars or {},
-                mcp=cast(Any, mcp) if mcp is not None else UNSET,
+                mcp=cast(Any, mcp) or UNSET,
                 secure=secure,
                 allow_internet_access=allow_internet_access,
                 network=SandboxNetworkConfig(**network) if network else UNSET,

packages/python-sdk/e2b/sandbox_sync/sandbox_api.py

@@ -170,7 +170,7 @@ def _create_sandbox(
                 metadata=metadata or {},
                 timeout=timeout,
                 env_vars=env_vars or {},
-                mcp=cast(Any, mcp) if mcp is not None else UNSET,
+                mcp=cast(Any, mcp) or UNSET,
                 secure=secure,
                 allow_internet_access=allow_internet_access,
                 network=SandboxNetworkConfig(**network) if network else UNSET,