Tool Use & Function Calling
How do you return a tool result to Claude?
QUICK ANSWER
Return tool results in a user message block containing a list of content blocks of type 'tool_result'. Each block must specify the matching 'tool_use_id' to bind the result to the initial request.
Request Payload Example
{
"role": "user",
"content": [
{
"type": "tool_result",
"tool_use_id": "toolu_01A2B3C4D5",
"content": "The current weather in Denver is 72°F and sunny."
}
]
}
Verified against: Anthropic API Tool Use v1