diff --git a/fastmcp_slim/fastmcp/cli/apps_dev.py b/fastmcp_slim/fastmcp/cli/apps_dev.py
index 2bfa5f1dc..49cbc771d 100644
--- a/fastmcp_slim/fastmcp/cli/apps_dev.py
+++ b/fastmcp_slim/fastmcp/cli/apps_dev.py
@@ -1221,7 +1221,7 @@ async def _list_tools(mcp_url: str) -> list[dict[str, Any]]:
             async with ClientSession(read, write) as session:
                 await session.initialize()
                 result = await session.list_tools()
-                return [t.model_dump() for t in result.tools]
+                return [t.model_dump(by_alias=True) for t in result.tools]
     except Exception as exc:
         logger.debug(f"Could not list tools from {mcp_url}: {exc}")
         return []
diff --git a/fastmcp_slim/fastmcp/server/event_store.py b/fastmcp_slim/fastmcp/server/event_store.py
index fb3c526df..7b988d61b 100644
--- a/fastmcp_slim/fastmcp/server/event_store.py
+++ b/fastmcp_slim/fastmcp/server/event_store.py
@@ -161,7 +161,7 @@ class EventStore(SDKEventStore):
         entry = EventEntry(
             event_id=event_id,
             stream_id=stream_id,
-            message=message.model_dump(mode="json") if message else None,
+            message=message.model_dump(mode="json", by_alias=True) if message else None,
         )
         await self._event_store.put(key=event_id, value=entry, ttl=self._ttl)
 
diff --git a/fastmcp_slim/fastmcp/server/providers/proxy.py b/fastmcp_slim/fastmcp/server/providers/proxy.py
index b757b6f2b..d4512f8ab 100644
--- a/fastmcp_slim/fastmcp/server/providers/proxy.py
+++ b/fastmcp_slim/fastmcp/server/providers/proxy.py
@@ -204,7 +204,9 @@ class ProxyTool(Tool):
                         if task_metadata:
                             meta = meta or {}
                             meta["modelcontextprotocol.io/task"] = (
-                                task_metadata.model_dump(exclude_none=True)
+                                task_metadata.model_dump(
+                                    by_alias=True, exclude_none=True
+                                )
                             )
 
                 result = await client.call_tool_mcp(
diff --git a/fastmcp_slim/fastmcp/server/transforms/prompts_as_tools.py b/fastmcp_slim/fastmcp/server/transforms/prompts_as_tools.py
index 28efbc658..81c421bc3 100644
--- a/fastmcp_slim/fastmcp/server/transforms/prompts_as_tools.py
+++ b/fastmcp_slim/fastmcp/server/transforms/prompts_as_tools.py
@@ -157,7 +157,9 @@ def _format_prompt_result(result: Any) -> str:
         if isinstance(msg.content, TextContent):
             content = msg.content.text
         else:
-            content = msg.content.model_dump(mode="json", exclude_none=True)
+            content = msg.content.model_dump(
+                mode="json", by_alias=True, exclude_none=True
+            )
 
         messages.append(
             {
diff --git a/fastmcp_slim/fastmcp/server/transforms/search/base.py b/fastmcp_slim/fastmcp/server/transforms/search/base.py
index 7368d62f5..cfeac6909 100644
--- a/fastmcp_slim/fastmcp/server/transforms/search/base.py
+++ b/fastmcp_slim/fastmcp/server/transforms/search/base.py
@@ -60,7 +60,8 @@ def _extract_searchable_text(tool: Tool) -> str:
 def serialize_tools_for_output_json(tools: Sequence[Tool]) -> list[dict[str, Any]]:
     """Serialize tools to the same dict format as ``list_tools`` output."""
     return [
-        tool.to_mcp_tool().model_dump(mode="json", exclude_none=True) for tool in tools
+        tool.to_mcp_tool().model_dump(mode="json", by_alias=True, exclude_none=True)
+        for tool in tools
     ]