Json Structured Output

An integrator wants strict JSON back and sets response_format to an invented {type:'json_schema'} value DeepSeek does not document, then treats the error as a bug.

Set response_format={type:'json_object'} — the documented DeepSeek JSON-output mode. The model then returns a JSON-parseable string. Do not pass undocumented response_format variants.

An integrator uses json_object mode to emulate tool dispatch, parsing the JSON to decide which internal function to run, while also declaring tools[].

Choose one mechanism: function calling (tools[]/tool_calls) for dispatch, or json_object for free-form structured extraction. Mixing a JSON-decoded pseudo-dispatch with declared tools creates two competing control paths — pick the one that matches the use case.

response_format=json_object is set but the prompt never mentions JSON or shows the desired shape; the output is empty or non-JSON.

Per docs, when using json_object the prompt must include the word 'json' and describe the expected schema/keys. Add an explicit instruction and an example shape; do not rely on response_format alone to induce well-formed JSON.