Extended Reasoning With Internal Thinking

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 “extended reasoning with thinking tokens”

Google's multimodal API — Gemini 2.5 Pro/Flash, 1M context, video understanding, grounding.

Unique: Allocates hidden 'thinking tokens' for internal reasoning before generating output, allowing the model to spend additional computation on difficult problems without exposing reasoning steps to the user

vs others: Similar to OpenAI's o1 extended reasoning, but integrated into the standard Gemini API rather than a separate model, allowing extended reasoning on the same multimodal inputs (images, audio, video) that standard Gemini supports

via “extended thinking with user-controlled reasoning effort”

Anthropic's balanced model for production workloads.

Unique: Implements hybrid reasoning with both user-controlled extended thinking and automatic adaptive thinking, allowing fine-grained effort control via API parameters rather than binary on/off toggle. This dual-mode approach enables cost optimization by letting developers choose reasoning depth per-request while maintaining automatic reasoning for complex queries.

vs others: Offers more granular reasoning control than GPT-4o's reasoning mode (which lacks effort parameters) and lower cost than o1 models while maintaining competitive reasoning performance on complex tasks.

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

Anthropic's developer console for Claude API.

Unique: Provides access to Claude's internal reasoning process via thinking blocks, allowing developers to inspect and debug Claude's reasoning rather than only seeing final outputs

vs others: More transparent than black-box reasoning in other LLMs, and allows developers to tune reasoning effort via budget parameters

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

text-generation model by undefined. 95,66,721 downloads.

Unique: Emergent chain-of-thought capability from instruction tuning on reasoning datasets; no explicit reasoning module or symbolic engine — reasoning emerges from learned token prediction patterns that favor intermediate explanation tokens, making it lightweight but probabilistic

vs others: Provides transparent reasoning comparable to GPT-4 on simple problems but with full local control; outperforms Mistral-7B on reasoning tasks due to instruction tuning, but lacks the formal verification and symbolic reasoning of specialized tools like Wolfram Alpha

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 reasoning with iterative refinement”

Opus 4.5 is not the normal AI agent experience that I have had thus far

Unique: Opus 4.5 exposes reasoning artifacts as first-class outputs that developers can inspect and interact with, rather than keeping reasoning internal — this enables debugging, validation, and guided refinement of agent decision-making in ways previous models obscured

vs others: Differs from standard LLM agents by making reasoning transparent and inspectable rather than treating it as a black box, enabling developers to understand failure modes and guide the model toward better solutions

via “multi-step reasoning with internal thought chains”

Proactive personal AI agent with no limits

Unique: Maintains explicit reasoning state across steps with backtracking capability, allowing the agent to revise earlier conclusions rather than committing to single-pass inference like most LLM-based agents

vs others: Provides better explainability than black-box agents by exposing intermediate reasoning, though at the cost of increased latency compared to single-pass inference approaches

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 “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-thinking-tokens”

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: Uses hidden thinking tokens that consume inference budget but remain invisible to users, enabling internal verification and multi-path exploration without exposing intermediate steps — distinct from chain-of-thought which exposes all reasoning to the user

vs others: Provides higher accuracy on complex reasoning tasks than standard LLMs while maintaining clean output formatting, though at higher latency and token cost than models without extended thinking capabilities

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 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 “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 “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 “hybrid-reasoning-with-internal-deliberation”

Hermes 4 is a large-scale reasoning model built on Meta-Llama-3.1-405B and released by Nous Research. It introduces a hybrid reasoning mode, where the model can choose to deliberate internally with...

Unique: Built on Llama-3.1-405B with learned routing that selectively activates internal deliberation pathways, allowing the model to choose reasoning depth per query rather than applying uniform extended thinking to all inputs. This contrasts with fixed-depth reasoning models like o1 that always use extended thinking.

vs others: Offers reasoning capabilities with adaptive compute allocation, reducing latency for simple queries compared to models with mandatory extended thinking, while maintaining deep reasoning for complex problems.

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 “extended reasoning with implicit chain-of-thought”

Grok 4 is xAI's latest reasoning model with a 256k context window. It supports parallel tool calling, structured outputs, and both image and text inputs. Note that reasoning is not...

Unique: Implicit reasoning allocation based on problem complexity, with reasoning traces integrated into output without explicit token budget management, contrasting with OpenAI's explicit reasoning token approach

vs others: More transparent reasoning than GPT-4o (which hides reasoning) but less controllable than o1 (which offers explicit reasoning token budgets); better for exploratory reasoning where depth is problem-dependent

via “extended-reasoning-chain-of-thought-generation”

ERNIE-4.5-21B-A3B-Thinking is Baidu's upgraded lightweight MoE model, refined to boost reasoning depth and quality for top-tier performance in logical puzzles, math, science, coding, text generation, and expert-level academic benchmarks.

Unique: Uses proprietary A3B (Adaptive Attention-Based Branching) mechanism that dynamically allocates compute across reasoning paths rather than fixed-depth chains, enabling adaptive reasoning depth based on problem complexity. This differs from static chain-of-thought approaches by treating reasoning as a branching tree with learned pruning heuristics.

vs others: Outperforms GPT-4 and Claude on mathematical reasoning benchmarks while maintaining 21B parameter efficiency through MoE architecture, making it faster and cheaper for reasoning-heavy workloads than larger closed-source models

via “hybrid-reasoning-with-explicit-thinking-mode”

DeepSeek-V3.1 is a large hybrid reasoning model (671B parameters, 37B active) that supports both thinking and non-thinking modes via prompt templates. It extends the DeepSeek-V3 base with a two-phase long-context...

Unique: Implements user-controlled explicit thinking via prompt templates rather than always-on reasoning, allowing per-request cost-performance optimization. The 37B active parameter subset processes thinking tokens in a separate phase before final generation, unlike models that interleave reasoning throughout decoding.

vs others: Offers finer-grained reasoning control than OpenAI o1 (which always reasons) and better cost efficiency than Claude 3.5 Sonnet's extended thinking by letting developers opt-in only when needed.