Hermes MCP / Tool Configuration (Windows)

When to use this skill

Load this skill when a user asks you to:

• Install or configure a new Hermes tool (computer-use, cua-driver, etc.)
• Add an MCP server to Hermes (hermes mcp add)
• Fix a broken MCP server connection
• Verify that a tool or MCP server is working
• Troubleshoot "tool not found" or "connection failed" errors

Canonical workflow

1. Install the underlying binary first

Most MCP servers need a native binary or npm package. Install it before
registering it with Hermes:

# cua-driver (computer-use)
hermes computer-use install

# Generic MCP server via npm
npm install -g @some/mcp-server

2. Register with Hermes via hermes mcp add

Use the add command — NOT hermes config set — for MCP servers that need
arguments:

hermes mcp add <name> \
  --command "<full-path-to-binary>" \
  --args arg1 arg2

The --args flag MUST be the last option. It produces a proper YAML list
(args: [arg1, arg2]).

3. Verify the connection

hermes mcp test <name>         # connection + tool discovery
hermes mcp list                # should show as ✓ enabled

4. Start a new session

MCP tools only appear in the next session (/reset in chat, or start a new
hermes invocation). They do NOT appear mid-conversation.

Known pitfalls

hermes config set serialises lists as strings

# ❌ WRONG — stored as a quoted string, connection fails silently
mcp_servers:
  my-server:
    command: "path\to\binary"
    args: '["mcp"]'    # string, not YAML list

Fix: remove and re-add with hermes mcp add:

hermes mcp remove <name>
hermes mcp add <name> --command "...<binary>" --args mcp

Do NOT use hermes config set mcp_servers.<name>.args [...] — the config set
command serialises array values as quoted YAML strings.

hermes mcp add requires interactive approval

The tool discovery step prompts "Enable all N tools? [Y/n/select]". To make
it non-interactive, pipe echo Y | as a prefix.

Full path required for Windows stdio servers

Always use the absolute path to the binary. Relative paths or bare names may
not resolve in the MCP server process's environment.

New session needed after adding/removing tools

MCP server changes and toolset toggles only take effect after /reset. If
the user reports a tool is "missing" after configuration, the session hasn't
been restarted.

Verification checklist

After any MCP tool setup, confirm each item:

• hermes mcp list — server shows as ✓ enabled
• hermes mcp test <name> — connection succeeds
• Binary's own health check passes (if available)
• /reset was performed (or new session started)
• The tool appears in the available tool list