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.

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.