MoonshotAI: Kimi K2 Thinking
Model Type
Proprietary Model
API access only
Recommended Use Cases
Try Kimi K2 Thinking
Overview
Kimi K2 Thinking is Moonshot AI's advanced reasoning model released in November 2025, designed for extended chain-of-thought reasoning while dynamically invoking tools across 200-300 sequential calls. K2 Thinking builds on the Kimi K2 base model with specialized training for agentic reasoning tasks. It reasons step-by-step while autonomously selecting from hundreds of available tools to complete complex tasks with minimal human intervention. The model cost approximately $4.6 million to train.
Key Features
- Extended reasoning: Deep chain-of-thought reasoning for complex problems
- Massive tool orchestration: Automatically selects and invokes 200-300 tools sequentially
- Stable long-horizon agency: Maintains coherent tool use across extended task sequences
- Native INT4 quantization: 2x inference speed through Quantization-Aware Training
- 256K context window: Supports long-horizon agentic tasks
Technical Specifications
| Specification | Value |
|---|---|
| Total Parameters | 1T |
| Active Parameters | 32B |
| Architecture | MoE (Mixture-of-Experts) |
| Context Length | 256K tokens |
| Training Cost | ~$4.6M |
Comparison with K2.5
Kimi K2 Thinking was released before K2.5 and focuses specifically on reasoning with tool use. K2.5 later incorporated these thinking capabilities along with native multimodality and Agent Swarm orchestration.
Availability
- API: Moonshot AI platform and third-party providers
- Open Weights: Hugging Face (moonshotai/Kimi-K2-Thinking)
- Kimi App: Available as thinking mode
Role in Series
Moonshot AI's Kimi models offer different capabilities:
- Kimi K2: Base agentic model, fastest
- Kimi K2 0905: Enhanced coding, 256K context
- Kimi K2 Thinking: Extended reasoning with massive tool use (this model)
- Kimi K2.5: Maximum capability with vision and Agent Swarm