# `Nous.Eval.Evaluators.ToolUsage`
[🔗](https://github.com/nyo16/nous/blob/v0.17.1/lib/nous/eval/evaluators/tool_usage.ex#L1)

Evaluator that verifies correct tool usage by the agent.

## Expected Format

    %{
      tools_called: ["tool_name1", "tool_name2"],
      tools_not_called: ["tool_name3"],
      output_contains: ["expected", "text"],
      min_tool_calls: 1,
      max_tool_calls: 5,
      tool_args: %{
        "tool_name" => %{"arg1" => "value1"}
      }
    }

All fields are optional.

## Configuration

  * `:strict_order` - Tools must be called in order (default: false)
  * `:check_args` - Verify tool arguments (default: true if tool_args provided)

## Examples

    # Verify specific tools were called
    TestCase.new(
      id: "tool_test",
      input: "What's the weather in Tokyo?",
      expected: %{
        tools_called: ["get_weather"],
        output_contains: ["Tokyo"]
      },
      eval_type: :tool_usage
    )

    # Verify tool call count
    TestCase.new(
      id: "multi_tool",
      input: "Compare weather in Tokyo and Paris",
      expected: %{
        tools_called: ["get_weather"],
        min_tool_calls: 2
      },
      eval_type: :tool_usage
    )

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*Consult [api-reference.md](api-reference.md) for complete listing*