Skip to main content
POST
https://api.matterai.so
/
v1
/
chat
/
completions
Chat
curl --request POST \
  --url https://api.matterai.so/v1/chat/completions \
  --header 'Content-Type: application/json' \
  --data '
{
  "model": "<string>",
  "messages": [
    {
      "role": "<string>",
      "content": "<string>"
    }
  ],
  "stream": true,
  "tools": [
    {
      "type": "<string>",
      "function": {
        "name": "<string>",
        "description": "<string>",
        "parameters": {}
      }
    }
  ],
  "tool_choice": "<string>",
  "max_tokens": 123,
  "reasoning": {
    "effort": "<string>",
    "summary": "<string>"
  },
  "response_format": {
    "type": "<string>"
  },
  "temperature": 123,
  "top_p": 123
}
'
{
  "400": {},
  "401": {},
  "429": {},
  "500": {},
  "id": "<string>",
  "object": "<string>",
  "created": 123,
  "model": "<string>",
  "choices": [
    {
      "index": 123,
      "message": {
        "role": "<string>",
        "content": "<string>"
      },
      "finish_reason": "<string>"
    }
  ],
  "usage": {
    "prompt_tokens": 123,
    "completion_tokens": 123,
    "total_tokens": 123
  }
}

​
Authentication

All API requests require authentication using a Bearer token. You can obtain your API key from the MatterAI Console. 
Authorization: Bearer MATTERAI_API_KEY
Keep your API key secure and never expose it in client-side code. Get your API key from the MatterAI console.

​
Request

​
model
string
required
The model to use for completion. Currently supports "axon".
​
messages
array
required
An array of message objects that make up the conversation.
​
stream
boolean
default:"false"
Whether to stream the response as it’s generated.
​
tools
array
A list of tools the model may call. Currently, only functions are supported as a tool type.
​
tool_choice
string
default:"auto"
Controls which (if any) tool is called by the model. Options: "none" means the model will not call any tool and instead generates a message. "auto" means the model can pick between generating a message or calling one or more tools. "required" means the model must call one or more tools. Specifying a particular tool via {"type": "function", "function": {"name": "my_function"}} forces the model to call that tool.
​
max_tokens
integer
default:"8192"
The maximum number of tokens to generate in the completion.
​
reasoning
object
Configuration for reasoning capabilities.
​
response_format
object
The format of the response.
​
temperature
number
default:"0.1"
Controls randomness in the output. Higher values make output more random, lower values make it more focused and deterministic. Range: 0.0 to 2.0.
​
top_p
number
default:"1"
Controls diversity via nucleus sampling. Range: 0.0 to 1.0.

​
Response

​
id
string
A unique identifier for the chat completion.
​
object
string
The object type, which is always "chat.completion".
​
created
integer
The Unix timestamp (in seconds) of when the chat completion was created.
​
model
string
The model used for the chat completion.
​
choices
array
A list of chat completion choices.
​
usage
object
Usage statistics for the completion request.

​
Example Request

curl --location 'https://api.matterai.so/v1/chat/completions' \
--header 'Content-Type: application/json' \
--header 'Authorization: Bearer MATTERAI_API_KEY' \
--data '{
    "model": "axon-code",
    "messages": [
        {
            "role": "system",
            "content": "You are a helpful assistant"
        },
        {
            "role": "user",
            "content": "Hi"
        }
    ],
    "stream": true,
    "tools": [
        {
            "type": "function",
            "function": {
                "name": "codebase_search",
                "description": "`codebase_search`: semantic search that finds code by meaning, not exact text",
                "parameters": {
                    "type": "object",
                    "properties": {
                        "explanation": {
                            "type": "string",
                            "description": "One sentence explanation as to why this tool is being used, and how it contributes to the goal."
                        },
                        "query": {
                            "type": "string",
                            "description": "A complete question about what you want to understand. Ask as if talking to a colleague: 'How does X work?', 'What happens when Y?', 'Where is Z handled?'"
                        },
                        "target_directories": {
                            "type": "array",
                            "items": {
                                "type": "string"
                            },
                            "description": "Prefix directory paths to limit search scope (single directory only, no glob patterns)"
                        },
                        "search_only_prs": {
                            "type": "boolean",
                            "description": "If true, only search pull requests and return no code results."
                        }
                    },
                    "required": [
                        "explanation",
                        "query",
                        "target_directories"
                    ]
                }
            }
        }
    ],
    "tool_choice": "auto",
    "max_tokens": 2000,
    "reasoning": {
        "effort": "none",
        "summary": "none"
    },
    "response_format": {
        "type": "text"
    },
    "temperature": 0.1,
    "top_p": 1
}'

​
Example Response

{
  "id": "chatcmpl-cd3ac60c-9746-457b-b4fa-aca53a993249",
  "choices": [
    {
      "index": 0,
      "message": {
        "role": "assistant",
        "content": "Axon is an Agentic LLM Model for coding by MatterAI, designed as an elite software engineering assistant for architecting mission-critical systems."
      },
      "finish_reason": "stop"
    }
  ],
  "created": 1756372473,
  "model": "axon-code",
  "object": "chat.completion",
  "usage": {
    "prompt_tokens": 47,
    "completion_tokens": 176,
    "total_tokens": 223,
    "completion_tokens_details": {
      "reasoning_tokens": 97
    },
    "prompt_tokens_details": {
      "cached_tokens": 25
    }
  }
}

​
Streaming

When stream is set to true, the API will return a stream of Server-Sent Events (SSE). Each event contains a JSON object with the partial response: 
data: {"id":"chatcmpl-abc123","object":"chat.completion.chunk","created":1677652288,"model":"axon","choices":[{"index":0,"delta":{"content":"Hello"},"finish_reason":null}]}

data: {"id":"chatcmpl-abc123","object":"chat.completion.chunk","created":1677652288,"model":"axon","choices":[{"index":0,"delta":{"content":"!"},"finish_reason":null}]}

data: {"id":"chatcmpl-abc123","object":"chat.completion.chunk","created":1677652288,"model":"axon","choices":[{"index":0,"delta":{},"finish_reason":"stop"}]}

data: [DONE]

​
Error Responses

The API returns standard HTTP status codes to indicate success or failure:
​
400
Bad Request
Invalid request parameters or malformed JSON.
​
401
Unauthorized
Invalid or missing API key.
​
429
Rate Limited
Too many requests. Please slow down.
​
500
Internal Server Error
Server error. Please try again later.
Example error response: 
{
  "error": {
    "message": "Invalid API key provided",
    "type": "invalid_request_error",
    "code": "invalid_api_key"
  }
}