feat: interactive MCP tool configuration in hermes tools (#1694)

Add the ability to selectively enable/disable individual MCP server
tools through the interactive 'hermes tools' TUI.

Changes:
- tools/mcp_tool.py: Add probe_mcp_server_tools() — lightweight function
  that temporarily connects to configured MCP servers, discovers their
  tools (names + descriptions), and disconnects. No registry side effects.

- hermes_cli/tools_config.py: Add 'Configure MCP tools' option to the
  interactive menu. When selected:
  1. Probes all enabled MCP servers for their available tools
  2. Shows a per-server curses checklist with tool descriptions
  3. Pre-selects tools based on existing include/exclude config
  4. Writes changes back as tools.exclude entries in config.yaml
  5. Reports which servers failed to connect

The existing CLI commands (hermes tools enable/disable server:tool)
continue to work unchanged. This adds the interactive TUI counterpart
so users can browse and toggle MCP tools visually.

Tests: 22 new tests covering probe function edge cases and interactive
flow (pre-selection, exclude/include modes, description truncation,
multi-server handling, error paths).

tests/hermes_cli/test_mcp_tools_config.py

@@ -0,0 +1,291 @@
+"""Tests for MCP tools interactive configuration in hermes_cli.tools_config."""
+
+from types import SimpleNamespace
+from unittest.mock import MagicMock, patch
+
+from hermes_cli.tools_config import _configure_mcp_tools_interactive
+
+# Patch targets: imports happen inside the function body, so patch at source
+_PROBE = "tools.mcp_tool.probe_mcp_server_tools"
+_CHECKLIST = "hermes_cli.curses_ui.curses_checklist"
+_SAVE = "hermes_cli.tools_config.save_config"
+
+
+def test_no_mcp_servers_prints_info(capsys):
+    """Returns immediately when no MCP servers are configured."""
+    config = {}
+    _configure_mcp_tools_interactive(config)
+    captured = capsys.readouterr()
+    assert "No MCP servers configured" in captured.out
+
+
+def test_all_servers_disabled_prints_info(capsys):
+    """Returns immediately when all configured servers have enabled=false."""
+    config = {
+        "mcp_servers": {
+            "github": {"command": "npx", "enabled": False},
+            "slack": {"command": "npx", "enabled": "false"},
+        }
+    }
+    _configure_mcp_tools_interactive(config)
+    captured = capsys.readouterr()
+    assert "disabled" in captured.out
+
+
+def test_probe_failure_shows_warning(capsys):
+    """Shows warning when probe returns no tools."""
+    config = {"mcp_servers": {"github": {"command": "npx"}}}
+    with patch(_PROBE, return_value={}):
+        _configure_mcp_tools_interactive(config)
+    captured = capsys.readouterr()
+    assert "Could not discover" in captured.out
+
+
+def test_probe_exception_shows_error(capsys):
+    """Shows error when probe raises an exception."""
+    config = {"mcp_servers": {"github": {"command": "npx"}}}
+    with patch(_PROBE, side_effect=RuntimeError("MCP not installed")):
+        _configure_mcp_tools_interactive(config)
+    captured = capsys.readouterr()
+    assert "Failed to probe" in captured.out
+
+
+def test_no_changes_when_checklist_cancelled(capsys):
+    """No config changes when user cancels (ESC) the checklist."""
+    config = {
+        "mcp_servers": {
+            "github": {"command": "npx", "args": ["-y", "server-github"]},
+        }
+    }
+    tools = [("create_issue", "Create an issue"), ("search_repos", "Search repos")]
+
+    with patch(_PROBE, return_value={"github": tools}), \
+         patch(_CHECKLIST, return_value={0, 1}), \
+         patch(_SAVE) as mock_save:
+        _configure_mcp_tools_interactive(config)
+    mock_save.assert_not_called()
+    captured = capsys.readouterr()
+    assert "no changes" in captured.out.lower()
+
+
+def test_disabling_tool_writes_exclude_list(capsys):
+    """Unchecking a tool adds it to the exclude list."""
+    config = {
+        "mcp_servers": {
+            "github": {"command": "npx"},
+        }
+    }
+    tools = [
+        ("create_issue", "Create an issue"),
+        ("delete_repo", "Delete a repo"),
+        ("search_repos", "Search repos"),
+    ]
+
+    # User unchecks delete_repo (index 1)
+    with patch(_PROBE, return_value={"github": tools}), \
+         patch(_CHECKLIST, return_value={0, 2}), \
+         patch(_SAVE) as mock_save:
+        _configure_mcp_tools_interactive(config)
+
+    mock_save.assert_called_once()
+    tools_cfg = config["mcp_servers"]["github"]["tools"]
+    assert tools_cfg["exclude"] == ["delete_repo"]
+    assert "include" not in tools_cfg
+
+
+def test_enabling_all_clears_filters(capsys):
+    """Checking all tools clears both include and exclude lists."""
+    config = {
+        "mcp_servers": {
+            "github": {
+                "command": "npx",
+                "tools": {"exclude": ["delete_repo"], "include": ["create_issue"]},
+            },
+        }
+    }
+    tools = [("create_issue", "Create"), ("delete_repo", "Delete")]
+
+    # User checks all tools — pre_selected would be {0} (include mode),
+    # so returning {0, 1} is a change
+    with patch(_PROBE, return_value={"github": tools}), \
+         patch(_CHECKLIST, return_value={0, 1}), \
+         patch(_SAVE) as mock_save:
+        _configure_mcp_tools_interactive(config)
+
+    mock_save.assert_called_once()
+    tools_cfg = config["mcp_servers"]["github"]["tools"]
+    assert "exclude" not in tools_cfg
+    assert "include" not in tools_cfg
+
+
+def test_pre_selection_respects_existing_exclude(capsys):
+    """Tools in exclude list start unchecked."""
+    config = {
+        "mcp_servers": {
+            "github": {
+                "command": "npx",
+                "tools": {"exclude": ["delete_repo"]},
+            },
+        }
+    }
+    tools = [("create_issue", "Create"), ("delete_repo", "Delete"), ("search", "Search")]
+    captured_pre_selected = {}
+
+    def fake_checklist(title, labels, pre_selected, **kwargs):
+        captured_pre_selected["value"] = set(pre_selected)
+        return pre_selected  # No changes
+
+    with patch(_PROBE, return_value={"github": tools}), \
+         patch(_CHECKLIST, side_effect=fake_checklist), \
+         patch(_SAVE):
+        _configure_mcp_tools_interactive(config)
+
+    # create_issue (0) and search (2) should be pre-selected, delete_repo (1) should not
+    assert captured_pre_selected["value"] == {0, 2}
+
+
+def test_pre_selection_respects_existing_include(capsys):
+    """Only tools in include list start checked."""
+    config = {
+        "mcp_servers": {
+            "github": {
+                "command": "npx",
+                "tools": {"include": ["search"]},
+            },
+        }
+    }
+    tools = [("create_issue", "Create"), ("delete_repo", "Delete"), ("search", "Search")]
+    captured_pre_selected = {}
+
+    def fake_checklist(title, labels, pre_selected, **kwargs):
+        captured_pre_selected["value"] = set(pre_selected)
+        return pre_selected  # No changes
+
+    with patch(_PROBE, return_value={"github": tools}), \
+         patch(_CHECKLIST, side_effect=fake_checklist), \
+         patch(_SAVE):
+        _configure_mcp_tools_interactive(config)
+
+    # Only search (2) should be pre-selected
+    assert captured_pre_selected["value"] == {2}
+
+
+def test_multiple_servers_each_get_checklist(capsys):
+    """Each server gets its own checklist."""
+    config = {
+        "mcp_servers": {
+            "github": {"command": "npx"},
+            "slack": {"url": "https://mcp.example.com"},
+        }
+    }
+    checklist_calls = []
+
+    def fake_checklist(title, labels, pre_selected, **kwargs):
+        checklist_calls.append(title)
+        return pre_selected  # No changes
+
+    with patch(
+        _PROBE,
+        return_value={
+            "github": [("create_issue", "Create")],
+            "slack": [("send_message", "Send")],
+        },
+    ), patch(_CHECKLIST, side_effect=fake_checklist), \
+         patch(_SAVE):
+        _configure_mcp_tools_interactive(config)
+
+    assert len(checklist_calls) == 2
+    assert any("github" in t for t in checklist_calls)
+    assert any("slack" in t for t in checklist_calls)
+
+
+def test_failed_server_shows_warning(capsys):
+    """Servers that fail to connect show warnings."""
+    config = {
+        "mcp_servers": {
+            "github": {"command": "npx"},
+            "broken": {"command": "nonexistent"},
+        }
+    }
+
+    # Only github succeeds
+    with patch(
+        _PROBE, return_value={"github": [("create_issue", "Create")]},
+    ), patch(_CHECKLIST, return_value={0}), \
+         patch(_SAVE):
+        _configure_mcp_tools_interactive(config)
+
+    captured = capsys.readouterr()
+    assert "broken" in captured.out
+
+
+def test_description_truncation_in_labels():
+    """Long descriptions are truncated in checklist labels."""
+    config = {
+        "mcp_servers": {
+            "github": {"command": "npx"},
+        }
+    }
+    long_desc = "A" * 100
+    captured_labels = {}
+
+    def fake_checklist(title, labels, pre_selected, **kwargs):
+        captured_labels["value"] = labels
+        return pre_selected
+
+    with patch(
+        _PROBE, return_value={"github": [("my_tool", long_desc)]},
+    ), patch(_CHECKLIST, side_effect=fake_checklist), \
+         patch(_SAVE):
+        _configure_mcp_tools_interactive(config)
+
+    label = captured_labels["value"][0]
+    assert "..." in label
+    assert len(label) < len(long_desc) + 30  # truncated + tool name + parens
+
+
+def test_switching_from_include_to_exclude(capsys):
+    """When user modifies selection, include list is replaced by exclude list."""
+    config = {
+        "mcp_servers": {
+            "github": {
+                "command": "npx",
+                "tools": {"include": ["create_issue"]},
+            },
+        }
+    }
+    tools = [("create_issue", "Create"), ("search", "Search"), ("delete", "Delete")]
+
+    # User selects create_issue and search (deselects delete)
+    # pre_selected would be {0} (only create_issue from include), so {0, 1} is a change
+    with patch(_PROBE, return_value={"github": tools}), \
+         patch(_CHECKLIST, return_value={0, 1}), \
+         patch(_SAVE):
+        _configure_mcp_tools_interactive(config)
+
+    tools_cfg = config["mcp_servers"]["github"]["tools"]
+    assert tools_cfg["exclude"] == ["delete"]
+    assert "include" not in tools_cfg
+
+
+def test_empty_tools_server_skipped(capsys):
+    """Server with no tools shows info message and skips checklist."""
+    config = {
+        "mcp_servers": {
+            "empty": {"command": "npx"},
+        }
+    }
+    checklist_calls = []
+
+    def fake_checklist(title, labels, pre_selected, **kwargs):
+        checklist_calls.append(title)
+        return pre_selected
+
+    with patch(_PROBE, return_value={"empty": []}), \
+         patch(_CHECKLIST, side_effect=fake_checklist), \
+         patch(_SAVE):
+        _configure_mcp_tools_interactive(config)
+
+    assert len(checklist_calls) == 0
+    captured = capsys.readouterr()
+    assert "no tools found" in captured.out