Question

You are building an assistant that lets Claude call a get_weather tool. In one turn, Claude returns a stop_reason of "tool_use" containing a single tool_use block requesting the weather for Denver. Your backend successfully retrieves the data. What must you send back to Claude so it can produce a final natural-language answer for the user?

Accepted Answer

A new user-role message containing a tool_result content block whose tool_use_id matches the id from Claude's tool_use block, with the weather data as its content.

Answer

A new assistant-role message containing the weather data as plain text, since the assistant is the one that requested the tool.

Answer

A system prompt update that appends the weather data so it is available on the next turn.

Answer

A new user-role message with a tool_use block that re-declares the get_weather tool and includes the retrieved data.