Only apply log config to FastMCP loggers

src/fastmcp/utilities/logging.py

@@ -20,15 +20,23 @@ def get_logger(name: str) -> logging.Logger:
 
 
 def configure_logging(
-    level: Literal["DEBUG", "INFO", "WARNING", "ERROR", "CRITICAL"] = "INFO",
+    level: Literal["DEBUG", "INFO", "WARNING", "ERROR", "CRITICAL"] | int = "INFO",
 ) -> None:
     """Configure logging for FastMCP.
 
     Args:
         level: the log level to use
     """
-    logging.basicConfig(
-        level=level,
-        format="%(message)s",
-        handlers=[RichHandler(console=Console(stderr=True), rich_tracebacks=True)],
-    )
+    # Only configure the FastMCP logger namespace
+    handler = RichHandler(console=Console(stderr=True), rich_tracebacks=True)
+    formatter = logging.Formatter("%(message)s")
+    handler.setFormatter(formatter)
+
+    fastmcp_logger = logging.getLogger("FastMCP")
+    fastmcp_logger.setLevel(level)
+
+    # Remove any existing handlers to avoid duplicates on reconfiguration
+    for hdlr in fastmcp_logger.handlers[:]:
+        fastmcp_logger.removeHandler(hdlr)
+
+    fastmcp_logger.addHandler(handler)

tests/utilities/test_logging.py

@@ -0,0 +1,30 @@
+import logging
+
+from fastmcp.utilities.logging import get_logger
+
+
+def test_logging_doesnt_affect_other_loggers(caplog):
+    # set FastMCP loggers to CRITICAL and ensure other loggers still emit messages
+    original_level = logging.getLogger("FastMCP").getEffectiveLevel()
+
+    try:
+        logging.getLogger("FastMCP").setLevel(logging.CRITICAL)
+
+        root_logger = logging.getLogger()
+        app_logger = logging.getLogger("app")
+        fastmcp_logger = logging.getLogger("FastMCP")
+        fastmcp_server_logger = get_logger("server")
+
+        with caplog.at_level(logging.INFO):
+            root_logger.info("--ROOT--")
+            app_logger.info("--APP--")
+            fastmcp_logger.info("--FASTMCP--")
+            fastmcp_server_logger.info("--FASTMCP SERVER--")
+
+        assert "--ROOT--" in caplog.text
+        assert "--APP--" in caplog.text
+        assert "--FASTMCP--" not in caplog.text
+        assert "--FASTMCP SERVER--" not in caplog.text
+
+    finally:
+        logging.getLogger("FastMCP").setLevel(original_level)