Docs / Connect / Hermes

Connect ModelBrain to Hermes

Hermes Agent keeps its MCP servers in a YAML file in your home folder, so connecting ModelBrain means adding one entry and reloading.

Hermes starts MCP servers with a trimmed environment, passing only what you list plus a safe baseline. That suits a memory tool that runs on your own computer with no account: there is no key to put in the file and nothing to leak through it.

Where the program lives

This client needs the full path to ModelBrain's mcp_server program. The commands and snippets on this page show the macOS path; on Windows or Linux, put the path for your system in the same place. Write the full path rather than a variable such as %LOCALAPPDATA% or ~, because a client may not expand it.

macOS

/Applications/ModelBrain.app/Contents/MacOS/mcp_server

Windows

C:\Users\you\AppData\Local\Programs\ModelBrain\mcp_server.exe (that is %LOCALAPPDATA%\Programs\ModelBrain\mcp_server.exe, with your own user name). Inside JSON, TOML or a quoted YAML string, double each backslash.

Linux

/home/you/.local/lib/modelbrain/mcp_server, with your own home folder. The install script puts ModelBrain in ~/.local/lib/modelbrain.

Steps

Install ModelBrain if you haven't yet (macOS, Windows or Linux).
Open ~/.hermes/config.yaml.
Add ModelBrain under mcp_servers. If you already have an mcp_servers section, add only the modelbrain entry inside it, lined up with the others. YAML cares about spaces, so use spaces and not tabs.
```
mcp_servers:
  modelbrain:
    command: "/Applications/ModelBrain.app/Contents/MacOS/mcp_server"
```
Reload. In a running Hermes session type /reload-mcp, or start a new session with hermes chat.
Check it is connected. ModelBrain's tools show up as mcp_modelbrain_ followed by the tool name. Ask Hermes to remember something, then recall it in a new session.

Questions

Where do I look if it does not connect?

Hermes writes the servers that registered, and the ones that failed with their error, to its agent log at startup. Check there first.

Can I limit which ModelBrain tools Hermes sees?

Yes. Hermes supports include and exclude lists per server in the same entry. We suggest leaving them off until you know which tools you want.

How do I undo it?

Remove the modelbrain entry, or set enabled to false. Your memories are not stored in that file.

Has this been tested?

We have tested this configuration against sample files and the ModelBrain setup code, but not yet by hand on a real install of Hermes. If ModelBrain does not appear in Hermes after you follow these steps, tell us through the Support page and we will fix this guide.

Not installed yet?

Start with the install guide.

Install ModelBrain →

Then

A 10-minute walkthrough: add a folder, ask something that needs two notes, see the citation.

Quickstart →