Chat Completions

The Mixedbread Chat Completions API is an OpenAI Chat Completions-compatible endpoint for Mixedbread specialized models and agentic workflows. When integrated with Mixedbread Search, the model can plan searches, inspect the returned evidence, and produce a grounded answer in a single API request.

You can use the OpenAI SDK by changing base_url and api_key, then selecting a model from the supported models.

PrerequisiteLink to section

Get a Mixedbread API key from the API Keys page. You can install the OpenAI SDK or use cURL directly.

export MXBAI_API_KEY=YOUR_API_KEY

Make your first requestLink to section

Point base_url to Mixedbread, use your Mixedbread API key, and select one supported model.

Create a chat completion

from openai import OpenAI

client = OpenAI(
    base_url="https://api.mixedbread.com/v1",
    api_key="YOUR_API_KEY",
)

completion = client.chat.completions.create(
    model="toast-1",
    messages=[
        {
            "role": "user",
            "content": "What is a search agent?",
        }
    ],
)

print(completion.choices[0].message.content)

Read the generated message from choices[0].message.

OpenAI compatibilityLink to section

Mixedbread accepts the OpenAI Chat Completions shape for supported fields. The tables below cover Mixedbread-specific extensions and behavior:

Request fieldsLink to section

Field or value	Behavior
`previous_completion_id`	Continues a stored completion and restores prior hosted-tool context when the supplied messages extend its history unchanged.
`max_tool_calls`	Limits the number of hosted retrieval calls for the completion.
`include`	Returns selected hosted-tool result payloads.
Hosted values in `tools` and `tool_choice`	Configures or requires Mixedbread-hosted Store tools.
`store`	Set to `false` to enable zero data retention. Completion content is not retained, and no retrievable completion is created. Operational model and token metadata is still recorded.

Response fieldsLink to section

Field	Behavior
`hosted_tool_calls`	Records server-side Store operations and optionally their results.
`title`	Returns the generated title of a stored conversation.
`choices[].message.reasoning_content`	Returns planning narration produced between hosted tool calls.

See every request and response field in the API reference.

Integrate with Mixedbread SearchLink to section

Mixedbread Search tools let Toast 1 plan and execute Store retrieval inside one completion request, then return a grounded answer without a client-side tool loop.

Integrate with Mixedbread Search

completion = client.chat.completions.create(
    model="toast-1",
    messages=[
        {
            "role": "user",
            "content": "What do my documents say about onboarding?",
        }
    ],
    extra_body={
        "tools": [
            {
                "type": "store_search",
                "store_identifiers": ["my-knowledge-base"],
            }
        ]
    },
)

print(completion.choices[0].message.content)

Mixedbread Search tools are opt-in: declare a tool in tools to turn it on for that completion, and scope its Store operations with store_identifiers. A completion that declares none runs no Store retrieval.

Search tool	Use it for
`store_search`	Semantic search across one or more Stores
`store_grep`	Exact text and regular expression matching
`store_list_chunks`	Metadata filtering, sorting, and chunk inspection
`store_metadata_facets`	Discovering metadata fields and representative values
`list_stores`	Discovering the Stores available to the API key

Use tool_choice to require a particular Mixedbread Search tool. max_tool_calls limits Mixedbread Search calls. Add a matching include value when your application needs retrieved chunk payloads in hosted_tool_calls.