GPT-5 is an intelligent reasoning model from OpenAI, designed for coding, reasoning, and agentic tasks across domains. It supports text and image inputs with text output, a 400,000-token context window, and up to 128,000 output tokens. With configurable reasoning effort, reasoning token support, streaming, function calling, Structured Outputs, and hosted tools such as web search, file search, image generation, code interpreter, and MCP, GPT-5 is well-suited for software engineering, complex reasoning, tool-based workflows, long-context applications, autonomous agents, and production-grade AI assistants.
Create chat completion
All API requests must be authenticated using a Bearer token in the Authorization header. Please ensure your API key is active.Authorization: Bearer sk-xxxxxx
These parameters come from the selected model form_schema. Switching models updates this list and the request example.
system_prompt?stringGlobal instructions or persona for the model.
prompt*stringimage_urls?arraySupports multi-image understanding (optional).
image_detail?stringreasoning_effort?stringControls how much reasoning effort the model spends before answering.
verbosity?stringControls how verbose the response is.
max_completion_tokens?numberresponse_format?stringstream?booleanid?stringParameter description for Id
object?stringParameter description for Object
created?integerParameter description for Created
model?stringModel ID used
choices?arrayParameter description for Choices
usage?objectParameter description for Usage
prompt_tokens?integerParameter description for Prompt Tokens
completion_tokens?integerParameter description for Completion Tokens
total_tokens?integerParameter description for Total Tokens
prompt_tokens_details?objectParameter description for Prompt Tokens Details
completion_tokens_details?objectParameter description for Completion Tokens Details
system_fingerprint?stringParameter description for System Fingerprint
error?objectParameter description for Error
message?stringError Message
type?stringError Type
param?stringRelated Parameters
code?stringError Code
error?objectParameter description for Error
message?stringError Message
type?stringError Type
param?stringRelated Parameters
code?stringError Code