Add Hadron to Claude Code (OAuth)¶

This is the shortest path to connect Claude Code to Hadron. You run one command, sign in once in your browser, and you're done. No API keys, no config files to download, nothing to copy-paste.

Follow the steps in order. Don't skip Step 2 — that's the step that actually signs you in.

Before you start¶

A Hadron account at hadronmemory.com. If you don't have one, create it first and confirm you can log in.
Claude Code installed. If claude --version prints a version, you're set. If not, install it with npm install -g @anthropic-ai/claude-code.

Step 1 — Register the Hadron MCP server¶

Run this in any terminal:

claude mcp add --transport http hadron https://srv.hadronmemory.com/mcp

This registers hadron for your user account, so it's available in every project on your machine. It does not sign you in yet — it just tells Claude Code where Hadron is.

If you see server already exists, you've added it before. Jump to Step 2.

Sign-in is done with the /mcp command inside Claude Code. This is the documented way to authenticate an OAuth MCP server in Claude Code.

Start Claude Code in any directory:
```
claude
```
At the prompt, type:
```
/mcp
```
Select hadron from the list. Claude Code opens your browser to the Hadron sign-in page.
Sign in (via GitHub if prompted), review the consent screen, and click Approve.
The browser shows a success message. Back in Claude Code, hadron now shows as connected in the /mcp panel.

That's it. Your token is stored and refreshed automatically — you won't be asked again unless you revoke access.

Step 3 — Verify it works¶

Still in Claude Code, type this as a normal message:

List my Hadron memories with h-list-memories.

Claude calls the h-list-memories tool and prints the memories your account can reach. If you see them, you're connected.

Just joined an organization?

You don't need to install an agent to read your org's shared memories. As soon as you're a member of an organization, its knowledge memories are readable over MCP — they show up in h-list-memories and you can open any node with h-read-node. Writing still requires a role granted through an App.

Only register Hadron once¶

You should have exactly one hadron server. Don't add a second registration and don't also enable a claude.ai Hadron connector pointing at the same URL — two entries for the same server cause confusing duplicate-auth behavior in the /mcp panel.

To check what's registered, run this in your shell (outside Claude Code):

claude mcp list

If hadron appears once, you're good.

If something goes wrong¶

The browser never opened¶

Repeat Step 2. If the window still doesn't appear, Claude Code prints the authorize URL — copy it into your browser, sign in, and approve.

You need to re-authenticate (or start clean)¶

Use Clear authentication in the /mcp menu to revoke the stored token, then run /mcp and authenticate again. Do this instead of removing and re-adding the server — it keeps you on a single registration.

`h-list-memories` returns nothing¶

An empty list means you're connected but your account can't reach any memories yet. If you've just created your account and aren't in an organization, that's expected — join or create an org and its shared memories will appear (no agent install required). If you are in an org and still see nothing, confirm you're signed in to the same Hadron account that belongs to that org. If you instead get 401 Unauthorized, your token was revoked; re-authenticate via Clear authentication → /mcp (above).

Claude asks which Hadron App to use¶

If your account belongs to more than one Hadron App, Claude may ask which one to use the first time it needs one. Just answer with the App you want — read tools like h-list-memories work without picking one.