diff --git a/src/fastmcp/client/transports.py b/src/fastmcp/client/transports.py
index 8817b134a..68544512a 100644
--- a/src/fastmcp/client/transports.py
+++ b/src/fastmcp/client/transports.py
@@ -2,6 +2,7 @@ import abc
 import contextlib
 import datetime
 import os
+import shutil
 from collections.abc import AsyncIterator
 from pathlib import Path
 from typing import (
@@ -343,6 +344,10 @@ class NpxStdioTransport(StdioTransport):
             env_vars: Additional environment variables
             use_package_lock: Whether to use package-lock.json (--prefer-offline)
         """
+        # verify npx is installed
+        if shutil.which("npx") is None:
+            raise ValueError("Command 'npx' not found")
+
         # Basic validation
         if project_directory and not Path(project_directory).exists():
             raise NotADirectoryError(
diff --git a/src/fastmcp/settings.py b/src/fastmcp/settings.py
index e82b75cc9..9d02b5d5a 100644
--- a/src/fastmcp/settings.py
+++ b/src/fastmcp/settings.py
@@ -42,7 +42,7 @@ class ServerSettings(BaseSettings):
     log_level: LOG_LEVEL = Field(default_factory=lambda: Settings().log_level)
 
     # HTTP settings
-    host: str = "0.0.0.0"
+    host: str = "127.0.0.1"
     port: int = 8000
     sse_path: str = "/sse"
     message_path: str = "/messages/"
diff --git a/tests/server/test_servers/fastmcp_server.py b/tests/test_servers/fastmcp_server.py
similarity index 100%
rename from tests/server/test_servers/fastmcp_server.py
rename to tests/test_servers/fastmcp_server.py
diff --git a/tests/server/test_servers/sse.py b/tests/test_servers/sse.py
similarity index 100%
rename from tests/server/test_servers/sse.py
rename to tests/test_servers/sse.py
diff --git a/tests/server/test_servers/stdio.py b/tests/test_servers/stdio.py
similarity index 100%
rename from tests/server/test_servers/stdio.py
rename to tests/test_servers/stdio.py