Claude Desktop

Claude Desktop can point at a custom endpoint through its Configure Third-Party Interface setting. That setting takes one base URL and one API key, with no model configuration at all, so it works with any provider your LLM Registry entry serves: Anthropic, OpenAI, Gemini, Bedrock, or OpenRouter.

The setting lives behind Claude Desktop's Developer menu, which is hidden by default. Step 1 turns it on.

Setup

1. Enable the Developer menu

The Developer menu doesn't appear in the menu bar until developer tools are allowed. Create the settings file that enables them:

echo '{ "allowDevTools": true }' > ~/Library/Application\ Support/Claude/developer_settings.json

caution

This command overwrites developer_settings.json. If you already have that file with other settings in it, open it in an editor instead and add "allowDevTools": true alongside what's already there.

2. Restart Claude Desktop

Quit Claude Desktop completely and reopen it. A Developer menu now appears in the menu bar.

3. Open Configure Third-Party Interface

Go to Developer → Configure Third-Party Interface, then set:

• Connection to Gateway
• Credential Kind to Static API Key

4. Enter the Gateway Base URL

https://<gateway-host>/llm/<url-prefix>

Via an Agent Persona, use the persona-scoped form instead:

https://<gateway-host>/p/<persona-id>/llm/<registry-entry-id>

note

Unlike the Cursor setup, this URL takes no /api/v1/cursor suffix. Paste the entry's endpoint URL exactly as the Connect flow shows it.

5. Enter the Gateway API Key, then save

Claude Desktop has exactly one credential field, so what goes in it depends on your entry's credential mode. Pick the tab that matches.

API Key

The gateway holds the provider credential, so the field carries your Agent Access Key on its own:

<your-agent-access-key>

An AWS SigV4 (Bedrock) entry works the same way, since the gateway holds those credentials too.

Passthrough (Agent Access Key Required)

The entry needs two credentials but Claude Desktop offers one field, so combine them, provider key first, separated by two colons:

<your-provider-key>::<your-agent-access-key>

The gateway splits the value apart before authenticating. See clients with only one credential field for why the order matters.

Passthrough (No Agent Access Key)

If the entry's Require an agent access key toggle is off, your provider key alone is enough:

<your-provider-key>

Save the setting. Claude Desktop now routes its model calls through the gateway.

Where to find each value

Placeholder	Where to find it
<gateway-host>	Host from the entry's Overview tab, for example gw.aigateway.example.com
<url-prefix>	The URL prefix field on the entry's Overview tab
<persona-id>	The persona's ID on the Agent Persona page
<registry-entry-id>	The entry's ID in the entry's URL
<your-agent-access-key>	Generate from the entry's Agent Access Keys step. Plaintext is shown once.
<your-provider-key>	Your own provider API key, needed only in passthrough mode

The entry's Connect flow shows the Claude Desktop steps with the real base URL and key already filled in, ready to copy.

Tips

• The Developer menu survives updates, the file may not. If the menu disappears after a Claude Desktop update, re-run the step 1 command and restart.
• Restart after step 1, not just a window close. Quit Claude Desktop fully. Closing the window leaves it running, and the menu won't appear.
• Check the two dropdowns if calls fail immediately. Connection must be Gateway and Credential Kind must be Static API Key. Any other combination sends a request shape the gateway endpoint doesn't expect.
• Two colons, no spaces. In the combined form, :: is the separator. A space on either side becomes part of the credential, and authentication fails.