fix(acp): allow hosts to skip configured MCP startup

acp_adapter/entry.py

@@ -32,6 +32,7 @@ else:
 import argparse
 import asyncio
 import logging
+import os
 import sys
 from pathlib import Path
 from hermes_constants import get_hermes_home
@@ -251,11 +252,13 @@ def main(argv: list[str] | None = None) -> None:
     # MCP servers dynamically via asyncio.to_thread inside the event
     # loop; that path is unaffected.)  Moved from model_tools.py module
     # scope to avoid freezing the gateway's loop on lazy import (#16856).
-    try:
-        from tools.mcp_tool import discover_mcp_tools
-        discover_mcp_tools()
-    except Exception:
-        logger.debug("MCP tool discovery failed at ACP startup", exc_info=True)
+    # Metadata-only hosts can opt out of unrelated global MCP startup.
+    if os.environ.get("HERMES_ACP_SKIP_CONFIGURED_MCP", "").strip() != "1":
+        try:
+            from tools.mcp_tool import discover_mcp_tools
+            discover_mcp_tools()
+        except Exception:
+            logger.debug("MCP tool discovery failed at ACP startup", exc_info=True)
 
     agent = HermesACPAgent()
     try:

tests/acp/test_entry.py

@@ -23,6 +23,50 @@ def test_main_enables_unstable_protocol(monkeypatch):
     assert calls["kwargs"]["use_unstable_protocol"] is True
 
 
+def test_main_skips_configured_mcp_discovery_when_requested(monkeypatch):
+    discovery_calls = []
+
+    async def fake_run_agent(agent, **kwargs):
+        pass
+
+    monkeypatch.setattr(entry, "_setup_logging", lambda: None)
+    monkeypatch.setattr(entry, "_load_env", lambda: None)
+    monkeypatch.setenv("HERMES_ACP_SKIP_CONFIGURED_MCP", "1")
+    monkeypatch.setattr(
+        "tools.mcp_tool.discover_mcp_tools",
+        lambda: discovery_calls.append(True),
+    )
+    monkeypatch.setattr(acp, "run_agent", fake_run_agent)
+
+    entry.main([])
+
+    assert discovery_calls == []
+
+
+@pytest.mark.parametrize("skip_value", [None, "", "0", "false"])
+def test_main_discovers_configured_mcp_when_skip_is_not_enabled(monkeypatch, skip_value):
+    discovery_calls = []
+
+    async def fake_run_agent(agent, **kwargs):
+        pass
+
+    monkeypatch.setattr(entry, "_setup_logging", lambda: None)
+    monkeypatch.setattr(entry, "_load_env", lambda: None)
+    if skip_value is None:
+        monkeypatch.delenv("HERMES_ACP_SKIP_CONFIGURED_MCP", raising=False)
+    else:
+        monkeypatch.setenv("HERMES_ACP_SKIP_CONFIGURED_MCP", skip_value)
+    monkeypatch.setattr(
+        "tools.mcp_tool.discover_mcp_tools",
+        lambda: discovery_calls.append(True),
+    )
+    monkeypatch.setattr(acp, "run_agent", fake_run_agent)
+
+    entry.main([])
+
+    assert discovery_calls == [True]
+
+
 def test_main_version_prints_without_starting_server(monkeypatch, capsys):
     monkeypatch.setattr(entry, "_setup_logging", lambda: (_ for _ in ()).throw(AssertionError("started server")))