diff --git a/tests/tools/test_toolsets.py b/tests/tools/test_toolsets.py
index d716c696d6dc1..2535099e14499 100644
--- a/tests/tools/test_toolsets.py
+++ b/tests/tools/test_toolsets.py
@@ -158,6 +158,33 @@ def test_mcp_alias_uses_live_registry(self, monkeypatch):
         assert validate_toolset("mcp-dynserver") is True
         assert "mcp__dynserver__ping" in resolve_toolset("dynserver")
 
+    def test_plugin_toolset_valid_before_discovery_finishes(self, monkeypatch):
+        """A configured plugin toolset must validate even while discovery is still in flight.
+
+        The live registry is empty until plugin discovery completes, so validating against it alone
+        reported a perfectly valid `-t <plugin>` as unknown on every fast startup and printed
+        "Warning: Unknown toolsets: <name>".
+        """
+        import hermes_cli.plugins as plugins
+
+        monkeypatch.setattr("tools.registry.registry", ToolRegistry())
+        monkeypatch.setattr(
+            plugins, "get_plugin_toolset_keys_nowait", lambda: {"dsh", "spotify"}, raising=False)
+
+        assert validate_toolset("dsh") is True
+        assert validate_toolset("spotify") is True
+
+    def test_declared_plugin_key_still_resolves_to_no_tools(self, monkeypatch):
+        """Name validation must not invent tools: an unloaded plugin toolset resolves empty."""
+        import hermes_cli.plugins as plugins
+
+        monkeypatch.setattr("tools.registry.registry", ToolRegistry())
+        monkeypatch.setattr(
+            plugins, "get_plugin_toolset_keys_nowait", lambda: {"dsh"}, raising=False)
+
+        assert validate_toolset("dsh") is True
+        assert resolve_toolset("dsh") == []
+
 
 class TestGetToolsetInfo:
     def test_leaf(self):
diff --git a/toolsets.py b/toolsets.py
index 1b2da7f579f92..49b065035193e 100644
--- a/toolsets.py
+++ b/toolsets.py
@@ -402,6 +402,23 @@ def _get_plugin_toolset_names() -> Set[str]:
     return {n for n in _registry_call("get_registered_toolset_names", ()) if n not in TOOLSETS}
 
 
+def _declared_plugin_toolset_names() -> Set[str]:
+    """Plugin toolset keys that a CONFIG may legitimately name, without joining discovery.
+
+    The live registry is empty until plugin discovery finishes, so validating a configured name
+    against it alone reports a valid plugin toolset (``-t dsh``) as unknown on every fast startup.
+    ``get_plugin_toolset_keys_nowait`` serves last launch's persisted set while a scan is in flight.
+    Only name validation uses this: a key with no live tools yet must still resolve to NO tools, so
+    ``get_toolset`` keeps reading the registry alone.
+    """
+    try:
+        from hermes_cli.plugins import get_plugin_toolset_keys_nowait
+
+        return set(get_plugin_toolset_keys_nowait())
+    except Exception:
+        return set()
+
+
 def _get_registry_toolset_aliases() -> Dict[str, str]:
     return _registry_call("get_registered_toolset_aliases", {})
 
@@ -438,7 +455,8 @@ def get_toolset_names() -> List[str]:
 
 def validate_toolset(name: str) -> bool:
     return (name in {"all", "*"} or name in TOOLSETS
-            or name in _get_plugin_toolset_names() or name in _get_registry_toolset_aliases())
+            or name in _get_plugin_toolset_names() or name in _get_registry_toolset_aliases()
+            or name in _declared_plugin_toolset_names())
 
 
 def create_custom_toolset(name: str, description: str, tools: List[str] = None, includes: List[str] = None) -> None: