Add enable_rich_logging setting to disable rich formatting (#2893)

Co-authored-by: claude[bot] <41898282+claude[bot]@users.noreply.github.com>
Co-authored-by: Bill Easton <strawgate@users.noreply.github.com>

src/fastmcp/settings.py

@@ -195,6 +195,18 @@ class Settings(BaseSettings):
 
     docket: DocketSettings = DocketSettings()
 
+    enable_rich_logging: Annotated[
+        bool,
+        Field(
+            description=inspect.cleandoc(
+                """
+                If True, will use rich formatting for log output. If False,
+                will use standard Python logging without rich formatting.
+                """
+            )
+        ),
+    ] = True
+
     enable_rich_tracebacks: Annotated[
         bool,
         Field(

src/fastmcp/utilities/logging.py

@@ -57,6 +57,18 @@ def configure_logging(
     logger.propagate = False
     logger.setLevel(level)
 
+    # Remove any existing handlers to avoid duplicates on reconfiguration
+    for hdlr in logger.handlers[:]:
+        logger.removeHandler(hdlr)
+
+    # Use standard logging handlers if rich logging is disabled
+    if not fastmcp.settings.enable_rich_logging:
+        # Create a standard StreamHandler for stderr
+        handler = logging.StreamHandler()
+        handler.setFormatter(logging.Formatter("%(levelname)s: %(message)s"))
+        logger.addHandler(handler)
+        return
+
     # Configure the handler for normal logs
     handler = RichHandler(
         console=Console(stderr=True),
@@ -91,10 +103,6 @@ def configure_logging(
 
     traceback_handler.addFilter(lambda record: record.exc_info is not None)
 
-    # Remove any existing handlers to avoid duplicates on reconfiguration
-    for hdlr in logger.handlers[:]:
-        logger.removeHandler(hdlr)
-
     logger.addHandler(handler)
     logger.addHandler(traceback_handler)
 

tests/utilities/test_logging.py

@@ -1,5 +1,6 @@
 import logging
 
+import fastmcp
 from fastmcp.utilities.logging import configure_logging, get_logger
 
 
@@ -54,3 +55,46 @@ def test_configure_logging_traceback_defaults_can_be_overridden():
     assert logger.handlers
     # The traceback handler should have been created with custom values
     # We can't directly inspect RichHandler internals easily, but we verified no error was raised
+
+
+def test_configure_logging_with_rich_disabled():
+    """Test that disabling rich logging uses standard StreamHandler."""
+    original_enable_rich = fastmcp.settings.enable_rich_logging
+    try:
+        fastmcp.settings.enable_rich_logging = False
+        configure_logging()
+
+        logger = logging.getLogger("fastmcp")
+        assert logger.handlers
+        # Should only have one handler when rich logging is disabled
+        assert len(logger.handlers) == 1
+        # Should be a StreamHandler, not RichHandler
+        assert isinstance(logger.handlers[0], logging.StreamHandler)
+        assert not hasattr(
+            logger.handlers[0], "console"
+        )  # RichHandler has console attribute
+    finally:
+        fastmcp.settings.enable_rich_logging = original_enable_rich
+        # Reconfigure to restore state
+        configure_logging()
+
+
+def test_configure_logging_with_rich_enabled():
+    """Test that enabling rich logging uses RichHandler."""
+    original_enable_rich = fastmcp.settings.enable_rich_logging
+    try:
+        fastmcp.settings.enable_rich_logging = True
+        configure_logging()
+
+        logger = logging.getLogger("fastmcp")
+        assert logger.handlers
+        # Should have two handlers when rich logging is enabled (normal + traceback)
+        assert len(logger.handlers) == 2
+        # Both should be RichHandler instances
+        from rich.logging import RichHandler
+
+        assert all(isinstance(h, RichHandler) for h in logger.handlers)
+    finally:
+        fastmcp.settings.enable_rich_logging = original_enable_rich
+        # Reconfigure to restore state
+        configure_logging()