diff --git a/run_agent.py b/run_agent.py
index 359a92185..244fea6b2 100644
--- a/run_agent.py
+++ b/run_agent.py
@@ -1224,14 +1224,27 @@ class AIAgent:
                 logger.warning("Memory provider plugin init failed: %s", _mpe)
                 self._memory_manager = None
 
-        # Inject memory provider tool schemas into the tool surface
+        # Inject memory provider tool schemas into the tool surface.
+        # Skip tools whose names already exist (plugins may register the
+        # same tools via ctx.register_tool(), which lands in self.tools
+        # through get_tool_definitions()).  Duplicate function names cause
+        # 400 errors on providers that enforce unique names (e.g. Xiaomi
+        # MiMo via Nous Portal).
         if self._memory_manager and self.tools is not None:
+            _existing_tool_names = {
+                t.get("function", {}).get("name")
+                for t in self.tools
+                if isinstance(t, dict)
+            }
             for _schema in self._memory_manager.get_all_tool_schemas():
+                _tname = _schema.get("name", "")
+                if _tname and _tname in _existing_tool_names:
+                    continue  # already registered via plugin path
                 _wrapped = {"type": "function", "function": _schema}
                 self.tools.append(_wrapped)
-                _tname = _schema.get("name", "")
                 if _tname:
                     self.valid_tool_names.add(_tname)
+                    _existing_tool_names.add(_tname)
 
         # Skills config: nudge interval for skill creation reminders
         self._skill_nudge_interval = 10
diff --git a/tests/agent/test_memory_provider.py b/tests/agent/test_memory_provider.py
index eba772a04..7e07d2f33 100644
--- a/tests/agent/test_memory_provider.py
+++ b/tests/agent/test_memory_provider.py
@@ -782,6 +782,49 @@ class TestOnMemoryWriteBridge:
         mgr.on_memory_write("remove", "memory", "old fact")
         assert p.memory_writes == [("remove", "memory", "old fact")]
 
+    def test_memory_manager_tool_injection_deduplicates(self):
+        """Memory manager tools already in self.tools (from plugin registry)
+        must not be appended again.  Duplicate function names cause 400 errors
+        on providers that enforce unique names (e.g. Xiaomi MiMo via Nous Portal).
+
+        Regression test for: duplicate mnemosyne_recall / mnemosyne_remember /
+        mnemosyne_stats in tools array → 400 from Nous Portal.
+        """
+        mgr = MemoryManager()
+        p = FakeMemoryProvider("ext", tools=[
+            {"name": "ext_recall", "description": "Recall", "parameters": {}},
+            {"name": "ext_remember", "description": "Remember", "parameters": {}},
+        ])
+        mgr.add_provider(p)
+
+        # Simulate self.tools already containing one of the plugin tools
+        # (as if it was registered via ctx.register_tool → get_tool_definitions)
+        existing_tools = [
+            {"type": "function", "function": {"name": "ext_recall", "description": "Recall (from registry)", "parameters": {}}},
+            {"type": "function", "function": {"name": "web_search", "description": "Search", "parameters": {}}},
+        ]
+
+        # Apply the same dedup logic from run_agent.py __init__
+        _existing_names = {
+            t.get("function", {}).get("name")
+            for t in existing_tools
+            if isinstance(t, dict)
+        }
+        for _schema in mgr.get_all_tool_schemas():
+            _tname = _schema.get("name", "")
+            if _tname and _tname in _existing_names:
+                continue
+            existing_tools.append({"type": "function", "function": _schema})
+            if _tname:
+                _existing_names.add(_tname)
+
+        # ext_recall should NOT be duplicated; ext_remember should be added
+        tool_names = [t["function"]["name"] for t in existing_tools]
+        assert tool_names.count("ext_recall") == 1, f"ext_recall duplicated: {tool_names}"
+        assert tool_names.count("ext_remember") == 1
+        assert tool_names.count("web_search") == 1
+        assert len(existing_tools) == 3  # web_search + ext_recall + ext_remember
+
     def test_on_memory_write_tolerates_provider_failure(self):
         """If a provider's on_memory_write raises, others still get notified."""
         mgr = MemoryManager()