From a46a476fe98c295fc6c5c5ab22ebcf9ba516352f Mon Sep 17 00:00:00 2001
From: Jeremiah Lowin <153965+jlowin@users.noreply.github.com>
Date: Tue, 23 Dec 2025 18:25:25 -0500
Subject: [PATCH] Let FastMCPError propagate unchanged from managers

---
 src/fastmcp/prompts/prompt_manager.py     |  7 +++----
 src/fastmcp/resources/resource_manager.py | 23 +++++++++--------------
 src/fastmcp/tools/tool_manager.py         | 12 +++++-------
 3 files changed, 17 insertions(+), 25 deletions(-)

diff --git a/src/fastmcp/prompts/prompt_manager.py b/src/fastmcp/prompts/prompt_manager.py
index 1563a1831f..e66c1e8783 100644
--- a/src/fastmcp/prompts/prompt_manager.py
+++ b/src/fastmcp/prompts/prompt_manager.py
@@ -7,7 +7,7 @@
 from mcp import GetPromptResult
 
 from fastmcp import settings
-from fastmcp.exceptions import NotFoundError, PromptError
+from fastmcp.exceptions import FastMCPError, NotFoundError, PromptError
 from fastmcp.prompts.prompt import FunctionPrompt, Prompt, PromptResult
 from fastmcp.settings import DuplicateBehavior
 from fastmcp.utilities.logging import get_logger
@@ -107,9 +107,8 @@ async def render_prompt(
         try:
             messages = await prompt.render(arguments)
             return GetPromptResult(description=prompt.description, messages=messages)
-        except PromptError as e:
-            logger.exception(f"Error rendering prompt {name!r}")
-            raise e
+        except FastMCPError:
+            raise
         except Exception as e:
             logger.exception(f"Error rendering prompt {name!r}")
             if self.mask_error_details:
diff --git a/src/fastmcp/resources/resource_manager.py b/src/fastmcp/resources/resource_manager.py
index 7367fb3e9c..28416a692a 100644
--- a/src/fastmcp/resources/resource_manager.py
+++ b/src/fastmcp/resources/resource_manager.py
@@ -10,7 +10,7 @@
 from pydantic import AnyUrl
 
 from fastmcp import settings
-from fastmcp.exceptions import NotFoundError, ResourceError
+from fastmcp.exceptions import FastMCPError, NotFoundError, ResourceError
 from fastmcp.resources.resource import Resource
 from fastmcp.resources.template import (
     ResourceTemplate,
@@ -268,10 +268,9 @@ async def get_resource(self, uri: AnyUrl | str) -> Resource:
                         uri_str,
                         params=params,
                     )
-                # Pass through ResourceErrors as-is
-                except ResourceError as e:
-                    logger.error(f"Error creating resource from template: {e}")
-                    raise e
+                # Pass through FastMCPErrors as-is
+                except FastMCPError:
+                    raise
                 # Handle other exceptions
                 except Exception as e:
                     logger.error(f"Error creating resource from template: {e}")
@@ -299,10 +298,9 @@ async def read_resource(self, uri: AnyUrl | str) -> str | bytes:
             try:
                 return await resource.read()
 
-            # raise ResourceErrors as-is
-            except ResourceError as e:
-                logger.exception(f"Error reading resource {uri_str!r}")
-                raise e
+            # raise FastMCPErrors as-is
+            except FastMCPError:
+                raise
 
             # Handle other exceptions
             except Exception as e:
@@ -322,11 +320,8 @@ async def read_resource(self, uri: AnyUrl | str) -> str | bytes:
                 try:
                     resource = await template.create_resource(uri_str, params=params)
                     return await resource.read()
-                except ResourceError as e:
-                    logger.exception(
-                        f"Error reading resource from template {uri_str!r}"
-                    )
-                    raise e
+                except FastMCPError:
+                    raise
                 except Exception as e:
                     logger.exception(
                         f"Error reading resource from template {uri_str!r}"
diff --git a/src/fastmcp/tools/tool_manager.py b/src/fastmcp/tools/tool_manager.py
index 9c6ee88604..e1d1f5c311 100644
--- a/src/fastmcp/tools/tool_manager.py
+++ b/src/fastmcp/tools/tool_manager.py
@@ -8,7 +8,7 @@
 from pydantic import ValidationError
 
 from fastmcp import settings
-from fastmcp.exceptions import NotFoundError, ToolError
+from fastmcp.exceptions import FastMCPError, NotFoundError, ToolError
 from fastmcp.settings import DuplicateBehavior
 from fastmcp.tools.tool import Tool, ToolResult
 from fastmcp.tools.tool_transform import (
@@ -158,12 +158,10 @@ async def call_tool(self, key: str, arguments: dict[str, Any]) -> ToolResult:
         tool = await self.get_tool(key)
         try:
             return await tool.run(arguments)
-        except ValidationError as e:
-            logger.exception(f"Error validating tool {key!r}: {e}")
-            raise e
-        except ToolError as e:
-            logger.exception(f"Error calling tool {key!r}")
-            raise e
+        except FastMCPError:
+            raise
+        except ValidationError:
+            raise
         except Exception as e:
             logger.exception(f"Error calling tool {key!r}")
             if self.mask_error_details: