Choose a harness and model
Choose the harness, model, and provider credential that your agent uses. For what each choice changes, see Harnesses and models.
Open the settings
Go to Sidebar > Agents > <agent name>, set Playground mode to Build, and open the Model & harness section at the top of the Configuration column. Its header summary shows the current harness and model, for example Pi · gpt-5.6-luna. A Connect key pill means no provider credential is set yet.
Use the inline panel to change the model or add a provider key. To change the harness or compare its available models and hosting options, click Detailed configuration.
Choose the harness
In the Model & harness dialog, open the Harness section. It offers Pi and Claude Code. The one in use carries a Current pill.
Each harness lists its supported providers under PROVIDERS and its hosting options under HOSTING. These lists reflect what is available in your deployment.
Each option also says whether it works with the model you have selected: ✓ supports your model, or ⚠ model not available.
If the harness you pick shows ⚠ model not available, the agent has no working model until you choose one in the Model section below.
Choose the model
Open the Model section and use the combobox. The list is filtered to the models the selected harness can reach, and choosing a model also sets its provider.
Search for a model or select a provider to see its models. If the provider is not listed, click + Add custom provider.
Choose the credential
The credential decides where the model runs. Open Provider credentials, which has two modes.
API key
Pick the provider tile, or one of the tiles under USE CUSTOM PROVIDER:
| Tile | Use it for |
|---|---|
The provider tile, for example OpenAI | The model vendor directly. Add the key and Agenta lists its models |
Azure OpenAI | Models served through Azure |
OpenAI-compatible endpoint | A proxy or gateway of your own that speaks the OpenAI API |
Paste the key into API key * and click Save. The key is encrypted in transit and at rest.
To manage keys for the whole project instead of one agent, go to Sidebar > Settings > LLMs. Each unconfigured provider has a Configure now button, and + OpenAI-compatible endpoint adds an endpoint of your own.
Subscription
The Subscription mode runs the agent against a Claude or ChatGPT subscription instead of a metered API key. It requires a self-hosted Agenta deployment, and the card is marked Unavailable in the cloud. See Use your own Claude or ChatGPT subscription.
Save and commit
Click Save in the dialog footer. The change is a draft on the agent configuration.
To publish it, click Commit in the Configuration header. Deployments and triggers run a pinned revision, so commit before an automation should use the new harness or model.