Using Cowork on 3P with an LLM Gateway

Configure Cowork on 3P to use Claude models on a self-hosted gateway that implements the Anthropic Messages API

To use a self-hosted LLM gateway (for example LiteLLM, Portkey, or an in-house proxy) as the inference provider, set inferenceProvider to gateway and supply the base URL and credentials described below.

The gateway must implement the Anthropic Messages API:

• POST /v1/messages with streaming and tool use is required.
• GET /v1/models is optional. If the gateway implements it, Cowork on 3P auto-discovers available models; if not, set inferenceModels explicitly.

The data-residency and “no conversation data sent to Anthropic” statements elsewhere in these pages apply to Vertex AI and Bedrock only. When you use a gateway, data handling is determined by the gateway you operate and the upstream provider it routes to.

Configuration keys

Setting	Required	Description
Gateway base URL inferenceGatewayBaseUrl	Yes	Gateway base URL. Must be https://.
Gateway API key inferenceGatewayApiKey	Unless using sso or a credential helper	API key sent to the gateway. The field cannot be empty, so if your gateway authenticates by network identity and does not require a key, set a placeholder value.
Gateway auth scheme inferenceGatewayAuthScheme	No	How the credential is sent. bearer (default) sends Authorization: Bearer <key>. x-api-key sends the x-api-key header instead. sso obtains the credential from the gateway’s own browser-based sign-in (OAuth 2.0 authorization server metadata at <inferenceGatewayBaseUrl>/.well-known/oauth-authorization-server and the device-authorization grant), in which case inferenceGatewayApiKey is not required.
Gateway extra headers inferenceGatewayHeaders	No	JSON string array of additional HTTP headers sent on every inference request, in "Name: Value" form, for example ["X-Org-Id: team1"].

As an alternative to a static inferenceGatewayApiKey, configure an inferenceCredentialHelper executable that prints the gateway credential to stdout.

Example

<key>inferenceProvider</key>
<string>gateway</string>
<key>inferenceGatewayBaseUrl</key>
<string>https://llm-gateway.example.corp</string>
<key>inferenceGatewayApiKey</key>
<string>your-gateway-key</string>