Anthropic Basic Reasoning

Compare a plain Claude agent with one using extended thinking, then inspect reasoning_content.

basic_reasoning.py
"""
Basic Reasoning
===============

Demonstrates this reasoning cookbook example.
"""

from agno.agent import Agent
from agno.models.anthropic import Claude
from rich.console import Console


# ---------------------------------------------------------------------------
# Create Example
# ---------------------------------------------------------------------------
def run_example() -> None:
    console = Console()

    # Classic reasoning test: comparing decimal numbers
    task = "9.11 and 9.9 -- which is bigger? Explain your reasoning step by step."

    # Create a regular agent (no reasoning)
    regular_agent = Agent(
        model=Claude(id="claude-sonnet-4-5"),
        markdown=True,
    )

    # Create an agent with extended thinking
    reasoning_agent = Agent(
        model=Claude(id="claude-sonnet-4-5"),
        reasoning_model=Claude(
            id="claude-sonnet-4-5",
            thinking={"type": "enabled", "budget_tokens": 1024},
        ),
        markdown=True,
    )

    console.rule("[bold blue]Regular Claude Agent (No Reasoning)[/bold blue]")
    console.print("This agent will answer directly without extended thinking.\n")
    regular_agent.print_response(task, stream=True)

    console.rule("[bold green]Claude with Extended Thinking[/bold green]")
    console.print("This agent uses extended thinking to analyze the problem deeply.\n")
    reasoning_agent.print_response(task, stream=True, show_full_reasoning=True)

    console.rule("[bold cyan]Accessing Reasoning Content[/bold cyan]")
    response = reasoning_agent.run(task, stream=False)
    if response.reasoning_content:
        console.print(
            f"[dim]Reasoning tokens used: {len(response.reasoning_content.split())}[/dim]"
        )
        console.print(
            f"\n[bold]First 300 chars of reasoning:[/bold]\n{response.reasoning_content[:300]}..."
        )


# ---------------------------------------------------------------------------
# Run Example
# ---------------------------------------------------------------------------
if __name__ == "__main__":
    run_example()

The archived len(response.reasoning_content.split()) expression counts whitespace-separated words in formatted display text. It does not measure billed tokens or private reasoning tokens. Label it "Display word count" in a local adaptation; use provider usage metrics, when available, for token accounting.

Run the Example

Set up your virtual environment

uv venv --python 3.12
source .venv/bin/activate

Install dependencies

uv pip install -U agno anthropic

Export your Anthropic API key

export ANTHROPIC_API_KEY="your_anthropic_api_key_here"

Run the example

Save the code above as basic_reasoning.py, then run:

python basic_reasoning.py

Full source: cookbook/10_reasoning/models/anthropic/basic_reasoning.py