Model Parameter Reference

Different model families have different defaults and constraints for Chat Completions API parameters. For the full model list, see the Model List.

Parameter Comparison

When temperature is close to 0, n can only be 1. Otherwise, the API returns invalid_request_error.

Model Parameter Differences

When switching models, you need to look beyond the model field — models differ in which request parameters they support and what defaults they use:

Parameter	`kimi-k3`	`kimi-k2.7-code`	`kimi-k2.6`	`kimi-k2.5`
Context window	1M tokens	256K tokens	256K tokens	256K tokens
`thinking`	—	May be omitted; if set explicitly, only `{"type":"enabled","keep":"all"}` is accepted	`{"type":"enabled"}` (default), `{"type":"disabled"}`, `{"type":"enabled","keep":"all"}`	`{"type":"enabled"}` (default), `{"type":"disabled"}`
`reasoning_effort`	`"low"` / `"high"` / `"max"` (default `"max"`)	Not supported	Not supported	Not supported
`tool_choice`	`auto` / `none` / `required`	`required` not supported	`required` not supported	—
`temperature`	Fixed at `1.0`	Fixed at `1.0`	`1.0` thinking / `0.6` non-thinking	`1.0` thinking / `0.6` non-thinking
`top_p`	Fixed at `0.95`	Fixed at `0.95`	Fixed at `0.95`	—
`n`	Fixed at `1`	Fixed at `1`	Fixed at `1`	—
`presence_penalty` / `frequency_penalty`	Fixed at `0`	Fixed at `0`	Fixed at `0`	—

“Fixed” means the parameter cannot be modified: passing any other value returns an error, so do not pass it explicitly.

`thinking`

thinking is a K2.x-only request parameter:

kimi-k2.6: supports {"type": "enabled"} (default), {"type": "disabled"}, and {"type": "enabled", "keep": "all"}.
kimi-k2.7-code: thinking is on by default and only {"type": "enabled", "keep": "all"} is accepted; any other configuration returns an error. When switching from kimi-k2.6, you must pass back the historical reasoning_content in messages as required by Preserved Thinking.

See Thinking Mode.

`reasoning_effort`

K3 always reasons with Preserved Thinking enabled. Configure its reasoning effort with the top-level reasoning_effort request field, which supports "low", "high", and "max" (default "max"). See Reasoning Effort.

Switching levels invalidates prefix-cache hits. Decide on the effort level before the conversation starts and avoid switching it mid-session.

`tool_choice`

kimi-k3 supports auto / none / required. kimi-k2.6 and kimi-k2.7-code do not support required and return an error if it is passed. See Tool Choice.

`temperature`

kimi-k2.6 / kimi-k2.5: fixed at 1.0 in thinking mode and 0.6 in non-thinking mode; other values return an error.
kimi-k2.7-code: fixed at 1.0; other values return an error.
kimi-k3: fixed at 1.0; other values return an error.

Do not pass temperature explicitly when calling these models. kimi-k2.7-code-highspeed is the same model as kimi-k2.7-code with identical parameter constraints; only the output speed differs.

FAQ

Switching from kimi-k2.6 to kimi-k3 — do I need to change my code? Replace model with kimi-k3 and remove the K2.x thinking configuration. To set the reasoning effort explicitly, use top-level reasoning_effort. In multi-turn conversations and tool calls, pass the complete assistant message returned by the API back to messages as-is, including any reasoning_content. Switching from kimi-k2.7-code to kimi-k3 — do I need to change my code? Replace model and continue passing complete assistant messages back as-is. To set the reasoning effort explicitly, use top-level reasoning_effort. My code uses OpenAI’s reasoning_effort — do I need to change it for kimi-k3? No. K3 supports top-level reasoning_effort with "low", "high", and "max" as accepted values and "max" as the default. Can I use tool_choice: "required" on kimi-k2.6 or kimi-k2.7-code? No. These models do not support required and return an error if it is passed; only kimi-k3 supports it.

Kimi K2.7 Code series — thinking Parameter

The kimi-k2.7-code series includes kimi-k2.7-code and its high-speed variant kimi-k2.7-code-highspeed; the two are the same model with identical parameter constraints (including the table above and the thinking behavior) and differ only in output speed (referred to collectively as kimi-k2.7-code below). kimi-k2.7-code is code-focused, and all parameter constraints except thinking are identical to kimi-k2.6. Unlike kimi-k2.6, its thinking is always on and cannot be disabled (passing {"type": "disabled"} errors), and Preserved Thinking is always on (thinking.keep is treated as "all" whether omitted or set to "all"; any other invalid value errors). So you do not need to pass the thinking parameter — just switch the model, and the model always emits reasoning_content. For details, see Using Thinking Mode.

Kimi K2.6 — thinking Parameter

Kimi K2.6 supports the thinking parameter to control whether deep thinking is enabled. Accepts {"type": "enabled"} or {"type": "disabled"}. Since the OpenAI SDK doesn’t have a native thinking parameter, use extra_body:

completion = client.chat.completions.create(
    model="kimi-k2.6",
    messages=[
        {"role": "user", "content": "Hello"}
    ],
    extra_body={
        "thinking": {"type": "disabled"}
    },
    max_tokens=1024*32,
)

curl https://api.moonshot.ai/v1/chat/completions \
  -H "Content-Type: application/json" \
  -H "Authorization: Bearer $MOONSHOT_API_KEY" \
  -d '{
    "model": "kimi-k2.6",
    "messages": [
      {"role": "user", "content": "Hello"}
    ],
    "thinking": {"type": "disabled"}
  }'

Using the API

API Reference

Files

Batch API

Parameter Comparison

Model Parameter Differences

`thinking`

`reasoning_effort`

`tool_choice`

`temperature`

FAQ

Kimi K2.7 Code series — thinking Parameter

Kimi K2.6 — thinking Parameter

​Parameter Comparison

​Model Parameter Differences

​thinking

​reasoning_effort

​tool_choice

​temperature

​FAQ

​Kimi K2.7 Code series — thinking Parameter

​Kimi K2.6 — thinking Parameter

Parameter Comparison

Model Parameter Differences

`thinking`

`reasoning_effort`

`tool_choice`

`temperature`

FAQ

Kimi K2.7 Code series — thinking Parameter

Kimi K2.6 — thinking Parameter