chat

Create a chat completion

Changed on Oct 8, 2026

Create a chat completion, optionally grounded in the caller's stores.

Supports the OpenAI Chat Completions API subset: a message list, function tools, streaming via server-sent events, and persistence via store. A request without hosted tools is one generation over exactly what was sent: no instructions, tools, or turns are added. The previous_completion_id groups stored turns into a conversation and restores the full model context; callers normally send only the new suffix. (previous_messages and terminal_tool_name are deprecated: resend the full edited history in messages instead.) Retrieval is opt-in: declare the hosted store tools (store_search, store_grep, store_list_chunks, store_metadata_facets, list_stores) in tools to let the model search, grep, filter, and read the caller's stores server-side, scoped by each declaration. Those executions are reported in the hosted_tool_calls extension field (and as extra streaming chunks), with chunk results included only for the requested include keys. A model call to a caller-declared function tool ends the completion with tool_calls on the choice message (finish_reason tool_calls); execute the functions and continue the conversation by appending the assistant message and the matching tool messages to the next request.

post/v1/chat/completions

Request

Base URL
https://api.mixedbread.com
URL
https://api.mixedbread.com/v1/chat/completions
Auth
HTTP bearer

Request body

modelstring

Public model ID. Defaults to toast-1

storeboolean

Whether to persist this completion for later retrieval

previous_completion_idstring nullable

ID of a stored completion this one continues (Mixedbread extension). Groups turns into a conversation for listing and deletion, and always restores the previous completion's full model context, including hosted tool calls and results

terminal_tool_namestring nullable

Deprecated and ignored. The stored transcript is never rewritten around a terminal tool call; the completion ends with the model's plain-text answer

streamboolean

Stream the completion as server-sent events

temperaturenumber nullable

top_pnumber nullable

max_completion_tokensinteger nullable

max_tokensinteger nullable

Deprecated alias of max_completion_tokens, honored when it is absent

max_tool_callsinteger nullable

Maximum number of server-handled tool calls (store tools and prune_context) executed for this completion; ignored when none are declared

parallel_tool_callsboolean

Whether the model may call multiple tools in one turn; when false, at most one is honored

metadataobject nullable

includestring[] nullable

Extra fields to include, e.g. search_corpus_call.results; unsupported values are ignored

Example request

{
  "tools": [
    {
      "filters": {
        "all": [
          {
            "key": "price",
            "operator": "gt",
            "value": "100"
          },
          {
            "key": "color",
            "operator": "eq",
            "value": "red"
          }
        ],
        "any": [
          {
            "key": "price",
            "operator": "gt",
            "value": "100"
          },
          {
            "key": "color",
            "operator": "eq",
            "value": "red"
          }
        ],
        "none": [
          {
            "key": "price",
            "operator": "gt",
            "value": "100"
          },
          {
            "key": "color",
            "operator": "eq",
            "value": "red"
          }
        ]
      }
    }
  ]
}

Response

The generated chat completion, or a server-sent event stream of completion chunks

idstring required

object'chat.completion'

createdinteger required

modelstring required

metadataobject nullable

titlestring nullable

Short display title of the conversation this completion belongs to (Mixedbread extension)

Changes

Oct 8, 2026e56cd129c68c Revision changes
- info
  the / request property's min was decreased from 16.00 to 1.00
- info
  the / request property's min was decreased from 16.00 to 1.00
Sep 23, 2026824e59bfac1e Revision changes
- breaking
  the //// request property type changed from object to no type
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  the ///// request property type changed from object to no type
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  added to the ///// response property oneOf list for the response status
- breaking
  added to the ///// response property oneOf list for the response status
- breaking
  the ///// response's property type changed from object to no type for status
- breaking
  the ///// response's property type changed from object to no type for status
- breaking
  removed the required property ////// from the response with the status
- breaking
  removed the required property ////// from the response with the status
- breaking
  removed the required property ////// from the response with the status
- breaking
  removed the required property ////// from the response with the status
- breaking
  removed the required property ////// from the response with the status
- breaking
  removed the required property ////// from the response with the status
- breaking
  removed the required property ////// from the response with the status
- breaking
  removed the required property ////// from the response with the status
- breaking
  removed the required property ////// from the response with the status
- breaking
  removed the required property ////// from the response with the status
- warning
  removed the request property /////
- warning
  removed the request property /////
- warning
  removed the request property /////
- warning
  removed the request property /////
- warning
  removed the request property /////
- warning
  removed the request property /////
- warning
  removed the request property //////
- warning
  removed the request property //////
- warning
  removed the request property //////
- warning
  removed the request property //////
- warning
  removed the request property //////
- warning
  removed the request property //////
- warning
  removed the optional property ////// from the response with the status
- warning
  removed the optional property ////// from the response with the status
- info
  added discriminator to //// request property
- info
  added discriminator to ///// request property
- info
  added to the //// request property oneOf list
- info
  added to the ///// request property oneOf list
- info
  added discriminator to ///// response property for the response status
- info
  added discriminator to ///// response property for the response status

Operation history (11 revisions)