> ## Documentation Index
> Fetch the complete documentation index at: https://evolink.ai/docs/llms.txt
> Use this file to discover all available pages before exploring further.
# Grok All-Model API - Chat Completions Reference
> - OpenAI-compatible Chat Completions endpoint for xAI Grok text models; pick the model via the `model` parameter (see the table on the `model` parameter for all values)
- `grok-4.5`: 500K-token context window; prompts of 200K tokens or more are billed at 2x for all token types
- Prompt caching is automatic: cached prompt tokens are billed at the lower cached-input rate
- Synchronous and streaming (SSE) modes
- Regular `function` tool calling is supported; xAI server-side tools are available on the [Responses API](../responses/responses-reference) only
**BaseURL**: The default BaseURL is `https://direct.evolink.ai`, which has better support for text models and long-lived connections. `https://api.evolink.ai` is the primary endpoint for multimodal services and serves as a fallback address for text models.
**Server-side tools** (web search, X search, code execution, attachment search, collections search) are only available on the [Responses API](../responses/responses-reference). The Chat Completions endpoint supports regular `function` tool calling only.
## OpenAPI
````yaml en/api-manual/language-series/grok/chat-completions/chat-completions-reference.json POST /v1/chat/completions
openapi: 3.1.0
info:
title: Grok All-Model API - Chat Completions Reference
description: >-
Full parameter reference for calling xAI Grok text models through the
OpenAI-compatible Chat Completions API.
license:
name: MIT
version: 1.0.0
servers:
- url: https://direct.evolink.ai
description: Production (recommended)
- url: https://api.evolink.ai
description: Alternative URL
security:
- bearerAuth: []
tags:
- name: Chat Completion
description: AI chat completion related APIs
paths:
/v1/chat/completions:
post:
tags:
- Chat Completion
summary: Grok Chat Completions (All Models, Full Parameters)
description: >-
- OpenAI-compatible Chat Completions endpoint for xAI Grok text models;
pick the model via the `model` parameter (see the table on the `model`
parameter for all values)
- `grok-4.5`: 500K-token context window; prompts of 200K tokens or more
are billed at 2x for all token types
- Prompt caching is automatic: cached prompt tokens are billed at the
lower cached-input rate
- Synchronous and streaming (SSE) modes
- Regular `function` tool calling is supported; xAI server-side tools
are available on the [Responses API](../responses/responses-reference)
only
operationId: grokChatCompletionsReference
requestBody:
required: true
content:
application/json:
schema:
$ref: '#/components/schemas/ChatCompletionRequest'
responses:
'200':
description: >-
Chat completion generated successfully (JSON object, or an SSE
stream of `chat.completion.chunk` events when `stream=true`)
content:
application/json:
schema:
$ref: '#/components/schemas/ChatCompletionResponse'
'400':
description: Invalid request parameters
content:
application/json:
schema:
$ref: '#/components/schemas/ErrorResponse'
example:
error:
code: 400
message: Invalid request parameters
type: invalid_request_error
'401':
description: Unauthorized, invalid or expired token
content:
application/json:
schema:
$ref: '#/components/schemas/ErrorResponse'
example:
error:
code: 401
message: Invalid or expired token
type: authentication_error
'402':
description: Insufficient quota, recharge required
content:
application/json:
schema:
$ref: '#/components/schemas/ErrorResponse'
example:
error:
code: 402
message: Insufficient quota
type: insufficient_quota_error
fallback_suggestion: https://evolink.ai/dashboard/billing
'429':
description: Rate limit exceeded
content:
application/json:
schema:
$ref: '#/components/schemas/ErrorResponse'
example:
error:
code: 429
message: Rate limit exceeded
type: rate_limit_error
fallback_suggestion: retry after 60 seconds
'500':
description: Internal server error
content:
application/json:
schema:
$ref: '#/components/schemas/ErrorResponse'
example:
error:
code: 500
message: Internal server error
type: internal_server_error
fallback_suggestion: try again later
'503':
description: Service temporarily unavailable
content:
application/json:
schema:
$ref: '#/components/schemas/ErrorResponse'
example:
error:
code: 503
message: Service temporarily unavailable
type: service_unavailable_error
fallback_suggestion: retry after 30 seconds
components:
schemas:
ChatCompletionRequest:
type: object
required:
- model
- messages
properties:
model:
type: string
description: |-
Model to call:
| Model ID | Positioning |
|---|---|
| `grok-4.5` | xAI reasoning + tool-use model, 500K context window |
enum:
- grok-4.5
example: grok-4.5
messages:
type: array
description: >-
List of chat messages. Supports `system`, `user`, and `assistant`
roles.
items:
$ref: '#/components/schemas/Message'
minItems: 1
example:
- role: system
content: You are a concise assistant.
- role: user
content: Explain prompt caching in one sentence.
stream:
type: boolean
description: >-
Whether to return a streaming response (SSE, `chat.completion.chunk`
events). Default `false`.
default: false
example: false
max_tokens:
type: integer
description: >-
Maximum number of tokens to generate. Passed through to the model
as-is.
example: 1024
temperature:
type: number
description: >-
Sampling temperature (0-2). Higher values produce more random
output.
example: 0.7
top_p:
type: number
description: Nucleus sampling parameter (0-1).
example: 0.95
tools:
type: array
description: >-
Regular OpenAI `function` tool definitions (client-side function
calling, no extra per-call fee). xAI server-side tools are only
available on the Responses API.
items:
$ref: '#/components/schemas/FunctionTool'
tool_choice:
description: >-
Controls function selection: `"auto"` / `"none"` / `"required"`, or
an object pinning a specific function.
oneOf:
- type: string
enum:
- auto
- none
- required
- type: object
ChatCompletionResponse:
type: object
properties:
id:
type: string
description: Unique identifier for the chat completion
example: chatcmpl-20260812164515123456789AbCdEfGh
model:
type: string
description: Model name actually used
example: grok-4.5
object:
type: string
enum:
- chat.completion
description: Response type
example: chat.completion
created:
type: integer
description: Creation timestamp
example: 1786538000
choices:
type: array
description: List of chat completion choices
items:
$ref: '#/components/schemas/Choice'
usage:
$ref: '#/components/schemas/Usage'
ErrorResponse:
type: object
properties:
error:
type: object
properties:
code:
type: integer
description: HTTP status error code
message:
type: string
description: Error description
type:
type: string
description: Error type
param:
type: string
description: Related parameter name
fallback_suggestion:
type: string
description: Suggestion when error occurs
Message:
type: object
required:
- role
- content
properties:
role:
type: string
description: Message role
enum:
- system
- user
- assistant
content:
type: string
description: Message content
FunctionTool:
type: object
required:
- type
- function
properties:
type:
type: string
enum:
- function
description: Tool type; the Chat Completions endpoint accepts `function` only
function:
type: object
description: >-
Function definition: `name`, `description`, and a JSON Schema
`parameters` object
Choice:
type: object
properties:
index:
type: integer
description: Choice index
example: 0
message:
$ref: '#/components/schemas/AssistantMessage'
finish_reason:
type: string
description: Finish reason
enum:
- stop
- length
- tool_calls
- content_filter
example: stop
Usage:
type: object
description: >-
Token usage statistics. Prompts of 200K tokens or more are billed at 2x
for all token types (input, cached input, output).
properties:
prompt_tokens:
type: integer
description: Number of tokens in input content
example: 504
completion_tokens:
type: integer
description: Number of tokens in output content
example: 2
total_tokens:
type: integer
description: Total number of tokens
example: 526
prompt_tokens_details:
type: object
description: Detailed input token information
properties:
cached_tokens:
type: integer
description: >-
Number of cached prompt tokens hit (billed at the lower
cached-input rate; caching is automatic)
example: 0
AssistantMessage:
type: object
properties:
role:
type: string
description: Message sender role
enum:
- assistant
example: assistant
content:
type: string
description: AI response message content
example: >-
Prompt caching reuses previously processed prompt prefixes so
repeated context is billed at a lower rate.
tool_calls:
type: array
description: >-
Function calls requested by the model (present when using `function`
tools)
items:
type: object
securitySchemes:
bearerAuth:
type: http
scheme: bearer
description: >-
##All APIs require Bearer Token authentication##
**Get API Key:**
Visit [API Key Management Page](https://evolink.ai/dashboard/keys) to
get your API Key
**Add to request header:**
```
Authorization: Bearer YOUR_API_KEY
```
````