How to Spot and Fix AI Hallucinations

import anthropic

client = anthropic.Anthropic()

# Instead of asking for conclusions directly, ask for explicit reasoning
def verify_claim(claim: str) -> str:
    response = client.messages.create(
        model="claude-sonnet-4-5",
        max_tokens=800,
        messages=[{
            "role": "user",
            "content": f"""Evaluate this claim step by step:

Claim: "{claim}"

Step 1: What do I actually know about this with confidence?
Step 2: What am I uncertain about?
Step 3: What would I need to verify to be sure?
Step 4: Overall assessment: Likely true / Uncertain / Likely false — and why.

Be explicit about uncertainty. Don't reach for confident answers."""
        }]
    )
    return response.content[0].text

result = verify_claim(
    "The Amazon rainforest produces 20% of the world's oxygen."
)
print(result)
# Returns: reasoning that reveals this is a common misconception —
# the Amazon absorbs roughly the same oxygen through decomposition as it produces