Grok 4.20 Multi-Agent - MixRoute API

Grok 4.20 Multi-Agent is xAI’s deep-research model in which multiple agents work in parallel and combine their results. Call grok-4.20-multi-agent-0309 through MixRoute using the OpenAI-compatible Responses API.

This model is not available through Chat Completions. Use POST /v1/responses; Chat Completions returns an endpoint error.

Key capabilities

Parallel agents - Multiple agents collaborate on the same research task
1M context window - Handles large source sets and long investigations
Reasoning and tools - Supports reasoning, function calling, and structured output
Multimodal input - Accepts text and images and returns text

Quick example

cURL
Python

curl "https://api.mixroute.ai/v1/responses" \
  -H "Authorization: Bearer YOUR_API_KEY" \
  -H "Content-Type: application/json" \
  -d '{
    "model": "grok-4.20-multi-agent-0309",
    "input": "Compare the main operational risks of three database migration strategies and produce a sourced recommendation.",
    "max_output_tokens": 512
  }'

from openai import OpenAI

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

response = client.responses.create(
    model="grok-4.20-multi-agent-0309",
    input="Compare the main operational risks of three database migration strategies and produce a sourced recommendation.",
    max_output_tokens=512,
)

print(response.output_text)

Parameters

Parameter	Type	Required	Description
`model`	string	Yes	Model ID: `grok-4.20-multi-agent-0309`.
`input`	string \| array	Yes	Text or structured multimodal input.
`max_output_tokens`	integer	No	Maximum output tokens.
`tools`	array	No	OpenAI-compatible tool definitions.

MixRoute may also list grok-4.20-multi-agent-beta-0309. Use the canonical grok-4.20-multi-agent-0309 ID shown above for new integrations.

Vendor reference

Grok 4.20 Multi-Agent documentation