diff --git a/hermes_cli/mcp_catalog.py b/hermes_cli/mcp_catalog.py
index 6566fa8276..b9355277db 100644
--- a/hermes_cli/mcp_catalog.py
+++ b/hermes_cli/mcp_catalog.py
@@ -561,7 +561,9 @@ def _apply_tool_selection(
         return
 
     if not probed:
-        _write_tools_filter(name, "include", None)
+        # Keep a prior explicit selection: "no tools today" must not widen ``include: []`` to
+        # "all tools" the next time the server does advertise some.
+        _write_tools_filter(name, "include", prior_selection)
         _say("  Server reported no tools.", Colors.YELLOW)
         return
 
diff --git a/tests/hermes_cli/test_mcp_catalog.py b/tests/hermes_cli/test_mcp_catalog.py
index 3367974e19..12f7886cbf 100644
--- a/tests/hermes_cli/test_mcp_catalog.py
+++ b/tests/hermes_cli/test_mcp_catalog.py
@@ -71,7 +71,7 @@ def _write_manifest(catalog_dir: Path, name: str, body: dict) -> Path:
     entry_dir = catalog_dir / name
     entry_dir.mkdir(exist_ok=True)
     path = entry_dir / "manifest.yaml"
-    with open(path, "w") as f:
+    with open(path, "w", encoding="utf-8") as f:
         yaml.safe_dump(body, f)
     return path
 
@@ -421,6 +421,24 @@ class TestInstall:
         assert server["tools"]["include"] == ["tool_a"]
         assert "exclude" not in server["tools"]
 
+    def test_empty_discovery_reinstall_keeps_explicit_empty_include(self, catalog_dir, monkeypatch):
+        """A probe that succeeds with zero tools must not widen a deliberate ``include: []``
+        to "all tools" (#12865): the block-all choice survives until the user changes it."""
+        import hermes_cli.mcp_catalog as mc
+        from hermes_cli.config import load_config, save_config
+
+        monkeypatch.setattr(mc, "_probe_tools", lambda name: [])
+        _write_manifest(catalog_dir, "demo", _basic_manifest())
+        cfg = load_config()
+        cfg.setdefault("mcp_servers", {})["demo"] = {
+            "command": "npx", "args": ["-y", "demo-mcp"], "enabled": True, "tools": {"include": []},
+        }
+        save_config(cfg)
+
+        mc.install_entry(_entry("demo"), enable=True)
+
+        assert load_config()["mcp_servers"]["demo"]["tools"]["include"] == []
+
     def test_probe_fail_reinstall_preserves_manual_exclude(self, catalog_dir):
         """A failed probe during reinstall keeps a hand-written
         tools.exclude on a manifest with no tool defaults, instead of
@@ -515,7 +533,7 @@ class TestInstall:
         # load_config resolves it; config.yaml itself stays secret-free.
         from hermes_cli.config import get_config_path
 
-        raw = get_config_path().read_text()
+        raw = get_config_path().read_text(encoding="utf-8")
         assert "${MCP_DEMO_API_KEY}" in raw
         assert "secret-val" not in raw