diff --git a/vllm_mlx/mcp/executor.py b/vllm_mlx/mcp/executor.py
index 18918158e..11c7afcbe 100644
--- a/vllm_mlx/mcp/executor.py
+++ b/vllm_mlx/mcp/executor.py
@@ -95,6 +95,10 @@ def __init__(
         self.default_timeout = default_timeout or manager.config.default_timeout
         self.validate_arguments = validate_arguments
         self.sandbox = sandbox or get_sandbox()
+        # Lazily-built lookup index: full_name and short name → MCPTool.
+        # Rebuilt whenever the tool count changes (e.g. after refresh_tools).
+        self._tool_index: dict[str, "MCPTool"] = {}
+        self._tool_index_size: int = -1
 
     async def execute_tool_calls(
         self,
@@ -119,17 +123,21 @@ async def execute_tool_calls(
         else:
             return await self._execute_sequential(tool_calls)
 
+    def _get_tool_index(self) -> dict[str, "MCPTool"]:
+        """Return a name→tool index, rebuilding it if the tool list changed."""
+        tools = self.manager.get_all_tools()
+        if len(tools) != self._tool_index_size:
+            idx: dict[str, "MCPTool"] = {}
+            for t in tools:
+                idx[t.full_name] = t
+                idx.setdefault(t.name, t)  # short name maps to first match
+            self._tool_index = idx
+            self._tool_index_size = len(tools)
+        return self._tool_index
+
     def _get_tool_by_name(self, full_name: str) -> Optional[MCPTool]:
         """Get a tool by its full name (server__tool or just tool)."""
-        for tool in self.manager.get_all_tools():
-            if tool.full_name == full_name:
-                return tool
-        # Try without server prefix
-        if "__" not in full_name:
-            for tool in self.manager.get_all_tools():
-                if tool.name == full_name:
-                    return tool
-        return None
+        return self._get_tool_index().get(full_name)
 
     def _validate_tool_call(self, tool_call: Dict[str, Any]) -> Optional[str]:
         """
@@ -186,11 +194,8 @@ def _get_server_for_tool(self, full_name: str) -> str:
         """Extract server name from full tool name or find it."""
         if "__" in full_name:
             return full_name.split("__")[0]
-        # Find which server has this tool
-        for tool in self.manager.get_all_tools():
-            if tool.name == full_name:
-                return tool.server_name
-        return "unknown"
+        tool = self._get_tool_index().get(full_name)
+        return tool.server_name if tool else "unknown"
 
     async def _execute_parallel(
         self,
@@ -465,18 +470,7 @@ def extract_and_validate(
 
     def _tool_exists(self, full_name: str) -> bool:
         """Check if a tool exists in any connected server."""
-        # Check by full name
-        for tool in self.manager.get_all_tools():
-            if tool.full_name == full_name:
-                return True
-
-        # Check by just tool name (without server prefix)
-        if "__" not in full_name:
-            for tool in self.manager.get_all_tools():
-                if tool.name == full_name:
-                    return True
-
-        return False
+        return full_name in self._get_tool_index()
 
 
 async def execute_single_tool(