Connect Codex and Claude over MCP

Server address

Every client uses the same server over HTTP. Sign-in uses OAuth, so you don’t need an API key.

MCP server URL URL

https://api.askneutron.com/mcp

Clients that read a JSON config file, such as a project’s .mcp.json, can use this entry:

.mcp.json JSON

{
  "mcpServers": {
    "neutron": {
      "type": "http",
      "url": "https://api.askneutron.com/mcp"
    }
  }
}

Claude Code

Add the server from your terminal:

Add the server to Claude Code Terminal

claude mcp add --transport http neutron https://api.askneutron.com/mcp

Then run /mcp in Claude Code, choose neutron, and sign in. To share the server with everyone working in a repository, commit the .mcp.json entry above instead.

Claude desktop and web

In Claude, open the settings for connectors and add a custom connector. Name it Neutron, paste the server URL, and connect. Claude opens askneutron so you can sign in.

Codex

Add the server, then sign in:

Add the server to Codex Terminal

codex mcp add neutron --url https://api.askneutron.com/mcp
codex mcp login neutron

Or add it to ~/.codex/config.toml yourself:

~/.codex/config.toml TOML

[mcp_servers.neutron]
url = "https://api.askneutron.com/mcp"

The first time a client connects, askneutron asks you to sign in, then shows what the client is asking for. Access applies to one organization and follows your current permissions.

Permission	What it allows
`neutron:search`	Search knowledge that you can access.
`neutron:tools`	Use Neutron tools in this client.
`neutron:actions`	Prepare actions that still need your confirmation. Optional.

Preparing actions is a separate checkbox. Even with it allowed, the client can’t run an action. It gets a link, and you check and confirm the action in Neutron before anything changes.

Tools

Tool	What it does	Inputs
`neutron_search`	Searches the company knowledge you can access and returns cited passages.	query (up to 2,000 characters), maxResults (1 to 20, default 8)
`neutron_fetch`	Returns the full source behind a citation from neutron_search, from the same version search used.	citationId, maxCharacters (1,000 to 200,000, default 50,000)
`neutron_prepare_action`	Prepares one action for you to check and confirm in Neutron. Only listed when you allow actions.	tool, arguments

Try a question that needs company knowledge, such as “Find our refund policy and cite the source.”

Disconnect a client

In the web app, open Settings, then Connected apps, and revoke the client. It stops working as you right away. You can connect it again later.

Connect Codex and Claude