IToolProvider Pattern

What it is

IToolProvider is an interface with a single method: IEnumerable<ITool> GetTools(). When you declare a partial class with [Tool] methods, the source generator emits a IToolProvider implementation automatically. You pass instances of your class directly to the Agent constructor via toolProviders:.

Problem it solves

Before IToolProvider, you had to reference generated wrapper type names directly:

// Old pattern — requires knowing generated type names
var agent = new Agent(model, tools: [
    new WeatherTools_GetWeather_Tool(new WeatherTools()),
    new WeatherTools_ConvertTemp_Tool(new WeatherTools())
]);

With IToolProvider, you pass the class itself:

// New pattern — no generated type names in user code
var agent = new Agent(model, toolProviders: [new WeatherTools()]);

The toolProviders: parameter accepts any IToolProvider. The agent calls GetTools() on each provider and registers all returned tools.

tools: vs toolProviders:

Parameter	Use when
toolProviders:	Passing your [Tool]-decorated classes (the common case)
tools:	Passing pre-built ITool instances — e.g., from agent.AsTool(), AgentCoreGatewayToolProvider, or McpToolProvider

Both can be used simultaneously:

var agent = new Agent(
    model: model,
    toolProviders: [new WeatherTools(), new SearchTools()],
    tools: [gatewayProvider.GetTools()..., researchAgent.AsTool("researcher", "...")]
);

DI registration

With Jacquard.Extensions.DI, register tool providers as services:

builder.Services
    .AddBedrockModel("us-east-1")
    .AddJacquardToolProvider<WeatherTools>()   // registers WeatherTools as IToolProvider
    .AddJacquardToolProvider<SearchTools>()
    .AddJacquardAgent();

AddJacquardAgent() resolves all registered IToolProvider instances and passes them to the Agent constructor automatically.

JACQUARD001 diagnostic

If you add [Tool] methods to a class that isn't partial, the source generator emits a JACQUARD001 warning:

warning JACQUARD001: Class 'WeatherTools' has [Tool] methods but is not declared partial.
Declare it partial to enable the IToolProvider pattern.

The per-method wrapper classes are still emitted so existing code keeps compiling, but the IToolProvider implementation is not generated. Add partial to the class declaration to resolve the warning.