agent-framework/dotnet/samples/04-hosting/FoundryHostedAgents/responses/Hosted-LocalTools

Hosted-LocalTools

A hosted agent with local C# function tools for hotel search. Demonstrates how to define and wire local tools that the LLM can invoke — a key advantage of code-based hosted agents over prompt agents.

The agent specializes in finding hotels in Seattle, with a GetAvailableHotels tool that searches a mock hotel database by dates and budget.

Prerequisites

• .NET 10 SDK
• An Azure AI Foundry project with a deployed model (e.g., gpt-4o)
• Azure CLI logged in (az login)

Configuration

Copy the template and fill in your project endpoint:

cp .env.example .env

Edit .env and set your Azure AI Foundry project endpoint:

AZURE_AI_PROJECT_ENDPOINT=https://<your-account>.services.ai.azure.com/api/projects/<your-project>
ASPNETCORE_URLS=http://+:8088
ASPNETCORE_ENVIRONMENT=Development
AZURE_AI_MODEL_DEPLOYMENT_NAME=gpt-4o

Note: .env is gitignored. The .env.example template is checked in as a reference.

Running directly (contributors)

This project uses ProjectReference to build against the local Agent Framework source.

cd dotnet/samples/04-hosting/FoundryHostedAgents/responses/Hosted-LocalTools
AGENT_NAME=hosted-local-tools dotnet run

The agent will start on http://localhost:8088.

Test it

Using the Azure Developer CLI:

azd ai agent invoke --local "Find me a hotel in Seattle for Dec 20-25 under $200/night"

Or with curl:

curl -X POST http://localhost:8088/responses \
  -H "Content-Type: application/json" \
  -d '{"input": "Find me a hotel in Seattle for Dec 20-25 under $200/night", "model": "hosted-local-tools"}'

Running with Docker

Since this project uses ProjectReference, use Dockerfile.contributor which takes a pre-published output.

1. Publish for the container runtime (Linux Alpine)

dotnet publish -c Debug -f net10.0 -r linux-musl-x64 --self-contained false -o out

2. Build the Docker image

docker build -f Dockerfile.contributor -t hosted-local-tools .

3. Run the container

Generate a bearer token on your host and pass it to the container:

# Generate token (expires in ~1 hour)
export AZURE_BEARER_TOKEN=$(az account get-access-token --resource https://ai.azure.com --query accessToken -o tsv)

# Run with token
docker run --rm -p 8088:8088 \
  -e AGENT_NAME=hosted-local-tools \
  -e AZURE_BEARER_TOKEN=$AZURE_BEARER_TOKEN \
  --env-file .env \
  hosted-local-tools

4. Test it

Using the Azure Developer CLI:

azd ai agent invoke --local "What hotels are available in Seattle for next weekend?"

How local tools work

The agent has a single tool GetAvailableHotels defined as a C# method with [Description] attributes. The LLM decides when to call it based on the user's request:

Parameter	Type	Description
checkInDate	string	Check-in date (YYYY-MM-DD)
checkOutDate	string	Check-out date (YYYY-MM-DD)
maxPrice	int	Max price per night in USD (default: 500)

The tool searches a mock database of 6 Seattle hotels and returns formatted results with name, location, rating, and pricing.

Deploying to Foundry (azd spec)

This sample includes an azd manifest (agent.manifest.yaml) and hosted agent spec (agent.yaml) for deployment to Foundry.

Initialize an azd project from this sample's manifest:

mkdir hosted-local-tools && cd hosted-local-tools
azd ai agent init -m https://github.com/microsoft/agent-framework/blob/main/dotnet/samples/04-hosting/FoundryHostedAgents/responses/Hosted-LocalTools/agent.manifest.yaml

Then deploy:

azd deploy

If you need to override defaults, set deployment-time environment variables in the azd environment before deploying:

azd env set AGENT_NAME hosted-local-tools
azd env set AZURE_AI_MODEL_DEPLOYMENT_NAME gpt-4o

For end-to-end hosted agent deployment guidance, see the official deployment guide.

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NuGet package users

If you are consuming the Agent Framework as a NuGet package (not building from source), use the standard Dockerfile instead of Dockerfile.contributor. See the commented section in HostedLocalTools.csproj for the PackageReference alternative.