Extended Thinking For Complex Reasoning And Problem Solving

via “extended thinking for complex reasoning and problem-solving”

Claude API — Opus/Sonnet/Haiku, 200K context, tool use, computer use, prompt caching.

Unique: Visible reasoning blocks show Claude's internal thought process, enabling transparency and verification of complex reasoning. Integrates seamlessly with all API features without requiring separate endpoints.

vs others: More transparent than OpenAI's chain-of-thought (which is hidden), enabling users to verify reasoning; comparable to o1 model's reasoning but available across Claude models with configurable depth

via “native chain-of-thought reasoning with extended thinking”

Google's most capable model with 1M context and native thinking.

Unique: Native thinking is baked into model architecture rather than achieved through prompt engineering; enables 94.3% accuracy on GPQA Diamond (scientific knowledge) without requiring explicit CoT prompting, and 77.1% on ARC-AGI-2 abstract reasoning puzzles

vs others: Outperforms GPT-4 and Claude 3.5 on reasoning benchmarks (GPQA 94.3% vs Sonnet 89.9%) because thinking is a first-class architectural feature, not a post-hoc prompt technique

via “extended-thinking code reasoning for complex problem-solving”

The frontier coding agent.

Unique: Explicitly exposes extended thinking as a selectable mode ('deep') within the agent, allowing developers to opt-in to slower but more thorough reasoning for complex problems. This is distinct from tools that use extended thinking transparently or not at all.

vs others: Provides explicit control over reasoning depth (smart/rush/deep modes) whereas Copilot uses a single model per request, and Cursor requires separate configuration or prompting to trigger deeper reasoning.

via “deep-reasoning-for-complex-queries”

Exclusively available on the OpenRouter API, Sonar Pro's new Pro Search mode is Perplexity's most advanced agentic search system. It is designed for deeper reasoning and analysis. Pricing is based...

Unique: Allocates extended reasoning resources specifically for complex queries, using iterative search and synthesis rather than single-pass retrieval. The system explicitly reasons about query complexity and adjusts reasoning depth accordingly.

vs others: Deeper reasoning than standard search APIs, and more adaptive than fixed-depth reasoning systems that apply the same analysis to all queries.

via “systematic reasoning support”

Provide systematic thinking, mental models, and debugging approaches to enhance problem-solving capabilities. Enable structured reasoning and decision-making support for complex problems. Facilitate integration with MCP-compatible clients for advanced cognitive workflows.

Unique: Utilizes a modular reasoning framework that allows for dynamic adjustment of mental models based on user input, enhancing adaptability.

vs others: More flexible than traditional reasoning tools as it allows for real-time adjustments to mental models based on user feedback.

via “extended-reasoning-with-internal-thinking”

Gemini 2.5 Pro is Google’s state-of-the-art AI model designed for advanced reasoning, coding, mathematics, and scientific tasks. It employs “thinking” capabilities, enabling it to reason through responses with enhanced accuracy...

Unique: Implements internalized thinking as part of the inference architecture rather than exposing chain-of-thought tokens, allowing the model to reason without token overhead while maintaining response quality. Uses adaptive computation allocation to balance reasoning depth with response latency based on problem complexity.

vs others: Provides reasoning benefits of extended chain-of-thought without the token cost and latency of explicit reasoning tokens, differentiating it from models like o1 that expose reasoning in the output stream.

via “iterative multi-step reasoning”

Break down complex problems into adjustable, multi-step reasoning. Plan, revise, and branch your approach while preserving context and filtering irrelevant details. Iterate toward a confident, verified solution when the scope is uncertain or evolving.

Unique: Utilizes a context-preserving architecture that allows for dynamic branching and filtering of irrelevant information, which is not commonly found in traditional reasoning tools.

vs others: More flexible than static reasoning frameworks, as it allows for real-time adjustments based on evolving problem contexts.

via “extended thinking reasoning with step-by-step problem decomposition”

Gemini 2.5 Pro is Google’s state-of-the-art AI model designed for advanced reasoning, coding, mathematics, and scientific tasks. It employs “thinking” capabilities, enabling it to reason through responses with enhanced accuracy...

Unique: Implements native extended thinking as a first-class capability integrated into the model architecture, allowing transparent reasoning-before-response without requiring prompt engineering or external chain-of-thought frameworks. The thinking process is computationally budgeted and automatically triggered based on query complexity.

vs others: Provides reasoning capabilities comparable to o1 but with broader multimodal support (image/audio inputs) and lower per-token cost than specialized reasoning models, though with less user control over reasoning depth.

via “extended reasoning with native thinking mode”

Gemini 2.5 Flash is Google's state-of-the-art workhorse model, specifically designed for advanced reasoning, coding, mathematics, and scientific tasks. It includes built-in "thinking" capabilities, enabling it to provide responses with greater...

Unique: Integrates reasoning as a first-class inference primitive rather than a prompt engineering technique, using an internal thinking phase that explores solution spaces before output generation, with separate token accounting for transparency

vs others: Provides more reliable reasoning than prompt-based CoT approaches (like o1-preview) while maintaining faster inference than full-chain reasoning models, with explicit visibility into thinking token usage

via “extended reasoning with chain-of-thought for complex visual tasks”

Qwen3-VL-30B-A3B-Thinking is a multimodal model that unifies strong text generation with visual understanding for images and videos. Its Thinking variant enhances reasoning in STEM, math, and complex tasks. It excels...

Unique: Integrates extended reasoning directly into the model's forward pass for visual tasks, rather than using post-hoc prompting techniques like 'think step-by-step', enabling the model to allocate compute dynamically to reasoning-heavy visual problems

vs others: More reliable than prompt-based chain-of-thought for visual reasoning because reasoning is baked into model weights, not dependent on prompt engineering; produces more consistent intermediate steps for STEM tasks

via “long-context reasoning with extended thinking”

Claude Opus 4.5 is Anthropic’s frontier reasoning model optimized for complex software engineering, agentic workflows, and long-horizon computer use. It offers strong multimodal capabilities, competitive performance across real-world coding and...

Unique: Implements internal chain-of-thought reasoning within a 200K token window using transformer attention mechanisms, allowing reasoning to occur before output generation without requiring explicit prompt engineering for step-by-step thinking

vs others: Outperforms GPT-4o and Claude 3.5 Sonnet on complex reasoning tasks by maintaining coherence across longer reasoning chains while keeping the 200K context window practical for real-world applications

via “reasoning and chain-of-thought task decomposition”

Step 3.5 Flash is StepFun's most capable open-source foundation model. Built on a sparse Mixture of Experts (MoE) architecture, it selectively activates only 11B of its 196B parameters per token....

Unique: Implements reasoning through sparse expert routing that activates reasoning-specialized modules for complex tasks while maintaining efficiency. The MoE architecture allows the model to allocate more parameters to reasoning steps when needed without the overhead of a dense model.

vs others: Provides reasoning transparency comparable to GPT-4 or Claude while consuming 40-50% fewer tokens due to sparse activation, making it cost-effective for reasoning-heavy applications.

via “logical reasoning and problem-solving with step-by-step decomposition”

Meta's latest class of model (Llama 3) launched with a variety of sizes & flavors. This 70B instruct-tuned version was optimized for high quality dialogue usecases. It has demonstrated strong...

Unique: Instruction-tuning explicitly optimizes for chain-of-thought reasoning patterns, enabling the model to articulate intermediate steps and self-correct. 70B scale provides sufficient capacity for multi-step reasoning without losing coherence.

vs others: Better reasoning transparency than smaller models and comparable to GPT-4 on many reasoning tasks at lower cost, though specialized reasoning models or symbolic solvers may outperform on highly constrained domains like formal mathematics.

via “reasoning and step-by-step problem solving”

GPT-3.5 Turbo is OpenAI's fastest model. It can understand and generate natural language or code, and is optimized for chat and traditional completion tasks. Training data up to Sep 2021.

Unique: Instruction-tuned for chain-of-thought reasoning, generating intermediate steps explicitly rather than jumping to conclusions; trained on diverse reasoning tasks to apply reasoning patterns across math, logic, and code domains

vs others: More accurate on multi-step problems than direct answer generation because explicit reasoning reduces errors; more flexible than specialized solvers because it handles diverse problem types, though less accurate than domain-specific tools (calculators, debuggers)

via “complex reasoning and chain-of-thought decomposition”

Command R7B (12-2024) is a small, fast update of the Command R+ model, delivered in December 2024. It excels at RAG, tool use, agents, and similar tasks requiring complex reasoning...

Unique: Command R7B's reasoning is optimized for RAG and tool-use contexts, where intermediate steps can reference retrieved documents or tool outputs, enabling grounded reasoning that combines external knowledge with logical inference

vs others: Outperforms GPT-4 on MATH and AIME benchmarks when combined with tool use for calculation, because it can delegate computation to tools rather than attempting symbolic math in-context

via “reasoning and multi-step problem solving”

A 12B parameter model with a 128k token context length built by Mistral in collaboration with NVIDIA. The model is multilingual, supporting English, French, German, Spanish, Italian, Portuguese, Chinese, Japanese,...

Unique: Mistral Nemo's instruction-tuning includes reasoning tasks and chain-of-thought examples, enabling it to generate explicit reasoning steps when prompted. The 128k context window enables longer reasoning chains than smaller-context models.

vs others: Reasoning capability is weaker than larger models (70B+) but sufficient for many reasoning tasks. Prompt-based chain-of-thought is more transparent than implicit reasoning but less efficient than specialized reasoning architectures.

via “reasoning-focused problem decomposition and chain-of-thought”

This is Mistral AI's flagship model, Mistral Large 2 (version mistral-large-2407). It's a proprietary weights-available model and excels at reasoning, code, JSON, chat, and more. Read the launch announcement [here](https://mistral.ai/news/mistral-large-2407/)....

Unique: Trained specifically on chain-of-thought datasets to prioritize reasoning steps, using attention mechanisms that weight intermediate reasoning tokens higher than direct answers, enabling more transparent problem-solving

vs others: Comparable to GPT-4's reasoning on complex problems, while maintaining lower latency and cost; outperforms Llama 2 on multi-step reasoning due to larger parameter count and specialized training

via “extended-chain-of-thought reasoning with explicit thinking tokens”

Qwen3-Max-Thinking is the flagship reasoning model in the Qwen3 series, designed for high-stakes cognitive tasks that require deep, multi-step reasoning. By significantly scaling model capacity and reinforcement learning compute, it...

Unique: Uses dedicated thinking token architecture with RL-optimized allocation strategy, allowing the model to dynamically determine reasoning depth per query rather than applying fixed reasoning budgets like some competitors. Separates internal deliberation from output generation at the token level, enabling transparent reasoning traces.

vs others: Provides deeper, more transparent reasoning than standard LLMs while maintaining faster inference than some reasoning-specialized models by using learned heuristics to allocate thinking compute only when needed.

via “agentic reasoning with extended chain-of-thought for complex problem decomposition”

Claude Opus 4 is benchmarked as the world’s best coding model, at time of release, bringing sustained performance on complex, long-running tasks and agent workflows. It sets new benchmarks in...

Unique: Opus 4's extended thinking uses internal reasoning tokens that guide computation without inflating output, enabling transparent multi-step reasoning that competitors expose as visible chain-of-thought text, making it more efficient and audit-friendly

vs others: Provides more reliable complex reasoning than GPT-4 on ambiguous problems because it explicitly works through constraints and dependencies before committing to solutions, reducing hallucination on edge cases

via “extended thinking for complex reasoning and problem-solving”

Claude Sonnet 4 significantly enhances the capabilities of its predecessor, Sonnet 3.7, excelling in both coding and reasoning tasks with improved precision and controllability. Achieving state-of-the-art performance on SWE-bench (72.7%),...

Unique: Allocates additional compute to internal reasoning before response generation using a gated reasoning mechanism, enabling exploration of multiple solution paths and self-validation without exposing intermediate reasoning, improving accuracy on complex tasks by 15-30% vs standard mode

vs others: More effective than explicit chain-of-thought prompting (which uses tokens in the output) and more efficient than ensemble approaches, with internal reasoning optimization that doesn't inflate output token counts while still improving solution quality