diff --git a/litellm/proxy/_experimental/mcp_server/semantic_tool_filter.py b/litellm/proxy/_experimental/mcp_server/semantic_tool_filter.py
index b6f6c7a87a0..a41678a6412 100644
--- a/litellm/proxy/_experimental/mcp_server/semantic_tool_filter.py
+++ b/litellm/proxy/_experimental/mcp_server/semantic_tool_filter.py
@@ -245,8 +245,8 @@ class SemanticMCPToolFilter:
           ``fc_web_search-firecrawl_scrape`` does match
           ``fc_web_search-firecrawl_scrape_a1b2c3d4`` but does not match
           ``fc_web_search-firecrawl_scrape_extra_tool`` (the part after the
-          canonical must be a single unique-ID segment, not another
-          ``<sep><tool_name>`` pair).
+          canonical contains a separator, indicating it's another
+          namespaced tool, not a unique-ID suffix).
 
         Both prefix and suffix matching are gated on ``canonical`` itself
         containing ``MCP_TOOL_PREFIX_SEPARATOR``. Server-registered MCP
@@ -288,7 +288,12 @@ class SemanticMCPToolFilter:
             # namespaced tool, not a unique-ID suffix.
             if remainder and remainder[0] in ("_", "-"):
                 rest = remainder[1:]
-                if MCP_TOOL_PREFIX_SEPARATOR not in rest:
+                # A unique-ID segment contains no separator at all (it's a
+                # short hex or alphanumeric string). Reject remainders that
+                # contain either underscore or dash, since both are valid
+                # separators in MCP tool names regardless of the configured
+                # MCP_TOOL_PREFIX_SEPARATOR.
+                if "_" not in rest and "-" not in rest:
                     return True
 
         return False
diff --git a/tests/test_litellm/proxy/_experimental/mcp_server/test_semantic_tool_filter.py b/tests/test_litellm/proxy/_experimental/mcp_server/test_semantic_tool_filter.py
index 4b02988a4dc..1b21210bd3f 100644
--- a/tests/test_litellm/proxy/_experimental/mcp_server/test_semantic_tool_filter.py
+++ b/tests/test_litellm/proxy/_experimental/mcp_server/test_semantic_tool_filter.py
@@ -681,8 +681,8 @@ class TestGetToolsByNames:
         """
         ``svc-search-extra_tool`` must NOT match canonical ``svc-search``
         because the remainder after the separator (``extra_tool``) itself
-        contains ``MCP_TOOL_PREFIX_SEPARATOR`` (``-``), indicating it is
-        another namespaced tool, not a unique-ID suffix.
+        contains a separator character (``_``), indicating it is another
+        namespaced tool, not a unique-ID suffix.
         """
         filter_instance = self._make_filter()
         available_tools = [