Agent Assertions

Validate tool/function calling behavior.

`tool_called(name, times=None)`


expect.tool_called("web_search")           # called at least once
expect.tool_called("web_search", times=1)  # called exactly once

`no_loop()`

Detects infinite loops in tool call traces.


expect.no_loop()

`tool_order(expected_tools)`

Checks tools were called in order.


expect.tool_order(["search", "parse", "summarize"])

Full example


@llm_test(
    expect.tool_called("web_search", times=1),
    expect.tool_called("summarize", times=1),
    expect.tool_order(["web_search", "summarize"]),
    expect.no_loop(),
    expect.cost_under(0.05),
    model="gpt-5-mini",
)
def test_research_agent(llm):
    tools = [
        {
            "type": "function",
            "function": {
                "name": "web_search",
                "description": "Search the web",
                "parameters": {
                    "type": "object",
                    "properties": {"query": {"type": "string"}},
                },
            },
        },
    ]
    output = llm("Research Python 3.14", tools=tools)
    assert output.tool_calls