> ## Documentation Index
> Fetch the complete documentation index at: https://hobbyist-e43fa225.mintlify.site/llms.txt
> Use this file to discover all available pages before exploring further.

# Update the model for a hosted agent

> Change the model deployment used by a Microsoft Foundry hosted agent and redeploy the project with Azure Developer CLI.

Change the AI model your hosted agent uses after initial deployment. Update the model deployment in `azure.yaml`, set the azd environment value that your agent reads at runtime, and redeploy the Microsoft Foundry hosted agent.

## Prerequisites

* An initialized and deployed hosted agent project. For setup, see [Initialize an agent project](/agents/init-agent-project) and [Deploy a hosted agent](/agents/deploy-hosted-agent).
* The [azd Foundry extensions installed](/developer-tools-and-integrations/install-cli-foundry-extensions).
* An authenticated `azd` session.
* A target model deployment name that is available for your Foundry project and region.

## Choose a model

When selecting a model, consider:

| Factor                  | Guidance                                                                                                                                                           |
| ----------------------- | ------------------------------------------------------------------------------------------------------------------------------------------------------------------ |
| **Task complexity**     | Use larger models for complex reasoning, tool use, and multistep tasks. Use smaller models (for example, `gpt-5.4-mini`) for simpler conversations and lower cost. |
| **Latency**             | Smaller models respond faster. If your agent needs quick responses, prefer mini/nano variants.                                                                     |
| **Cost**                | Model pricing varies significantly. Check the Azure AI pricing page for current rates.                                                                             |
| **Region availability** | Not all models are available in all regions. Verify availability in the Foundry portal before switching.                                                           |

## Update the environment variable

There is no dedicated command for updating the model yet. Start by updating the model deployment name in your azd environment:

```bash theme={null}
azd env set FOUNDRY_MODEL_NAME=gpt-5.4-mini
```

## Update azure.yaml

Model selection for hosted agents is defined in two places in `azure.yaml`:

* The `azure.ai.project` service defines the model deployment in its `deployments` list.
* The `azure.ai.agent` service defines the runtime environment variable that your agent code reads from the `env` map.

Update both entries to use the target deployment name:

```yaml theme={null}
services:
  ai-project:
    host: azure.ai.project
    deployments:
      - name: gpt-5.4-mini
        model:
          format: OpenAI
          name: gpt-5.4-mini
          version: "2026-03-17"
        sku:
          name: GlobalStandard
          capacity: 10
  my-agent:
    host: azure.ai.agent
    project: src/my-agent
    kind: hosted
    uses:
      - ai-project
    env:
      FOUNDRY_MODEL_NAME: ${FOUNDRY_MODEL_NAME}
```

The model deployment name in the azd environment should match the deployment name in `services.<project-service>.deployments[].name`.

## Redeploy the project

Run `azd up`:

```bash theme={null}
azd up
```

Use `azd up`, not just `azd deploy`, if the new model deployment needs to be provisioned. If the model deployment already exists in your Foundry project, `azd deploy` is sufficient.

<Tip>
  Run `azd env get-values` to see all current environment variables.
</Tip>

## Configure different models per environment

You can configure different models for development and production using azd environments:

```bash theme={null}
# Development environment
azd env select dev
azd env set FOUNDRY_MODEL_NAME=<development-model-deployment>

# Production environment
azd env select prod
azd env set FOUNDRY_MODEL_NAME=<production-model-deployment>
```

Each environment maintains its own set of variables in `.azure/<env-name>/.env`.

## Related content

* [Azure YAML reference](/agents/azure-yaml-reference) for deployment configuration details.
* [Deploy a hosted agent](/agents/deploy-hosted-agent) to understand how deployment works.