IA Anthropic – Claude

AI Anthropic – Claude: understanding the Anthropic model family

Introduction

The Claude family of models developed by Anthropic has become a serious competitor to American models such as GPT 4 and Gemini. Based on a transformative architecture and trained according to the Constitutional AI philosophy – an approach in which AI criticizes itself based on a “code of conduct” inspired by human rights – the various versions of Claude aim to produce secure, transparent and high-performance responsesen.wikipedia.org. With each successive version (Claude 1, 2, 3, 3.5, then 4 and 4.5), Anthropic has improved reasoning capacity, context duration and speed, while expanding the range of inputs (text, image, audio) and reducing the price of useibm.com.

History and versions

From Claude 1 to Claude 3.5

The first version of the model, Claude 1 (March 2023), was a generalist model designed to rival ChatGPT. A few months later, Claude 2 extended the context window to 100,000 tokens, enabled PDF downloads and improved response consistency.

In March 2024, Anthropic introduced Claude 3 and three variants: Haiku (fast and economical), Sonnet (balance between price and performance) and Opus (more powerful and more expensive). These templates are multimodal: they include text, images and documents, and can be used via API or web interface. Claude 3 has been trained on a larger corpus and includes enhanced security mechanisms thanks to Constitutional AI.

In June 2024, Anthropic launched Claude 3.5 Sonnet, an intermediate model offering up to twice the speed of Claude 3 Opus, a context of 200,000 tokens and a relatively low entry price (around $3 per million tokens). New functions, such as Artifacts, enable code or documents to be generated and shared directly in the interface.

Claude 4 and Claude 4.5

In May 2025, Anthropic introduced the Claude 4 generation (Opus 4 and Sonnet 4). These models enhance reasoning capabilities, use external tools in parallel, improve long memory and can handle complex tasks such as advanced programming.

Autumn 2025 sees the arrival of Claude 4.5, which targets professional customers. Reuters reports that this version can code autonomously for up to 30 hours, achieves increased performance in finance and science, and is intended as a response to the autonomous agents integrated into Microsoft 365 Copilot. Anthropic claims a significant reduction in computing costs thanks to a hybrid architecture and reinforced alignment.

Operation and key innovations

• Constitutional AI: Unlike other models that use onlyRLHF (reinforcement learning with human feedback), Claude relies on a set of 75 principles (constitution) that guide the model towards safe and ethical responses. The model is self-critical and reformulates its responses in the event of drift.
• Multimodality and long context window: Claude 3 and its successors accept long texts (200,000 tokens) and files (PDF, images, audio). This window makes it possible to analyze entire projects or voluminous codes without splitting them up, which is crucial for auditing and programming activities.
• Tools and APIs: From Claude 4 onwards, models can use external tools (web search, mathematical engines, databases) in parallel, considerably improving the accuracy and depth of answers.
• Artifacts and collaboration: on Claude 3.5 and higher, users can generate documents or code and collaborate in real time via artifacts.

Competitor comparison

According to several benchmarks, the Claude models rival GPT-4 and outperform the free versions of ChatGPT on general knowledge (MMLU) and coding tests. Despite their performance, they remain cautious: Anthropic voluntarily imposes restrictions to avoid potentially dangerous responses. This “alignment tax” sometimes translates into rejections or moralistic advice, which may frustrate developers, but reinforces security; this approach differentiates Claude from ChatGPT.

Use cases and integrations

Claude models are used in :

• Automation and authoring: generation of reports, articles, technical or sales documentation.
• Software development: assistance with coding (systems, web and data), debugging and step-by-step explanation of algorithms, with the ability to run unit tests and generate complete code.
• Customer service: creation of multilingual chatbots and ticket management.
• Research and analysis: synthesize scientific documents, check sources and answer complex questions.
• Education and training: interactive tutorials and pedagogical customization according to learner level.

Outlook

Anthropic’s roadmap includes Haiku 4.5 and Opus 4.5, as well as enhanced autonomous agent capabilities (agents capable of planning and executing actions). With increasing integration in office suites (Microsoft 365 Copilot) and enterprise APIs, Claude is establishing itself as a major player in the LLM market. Its open approach (freely accessible interface), ethical transparency and emphasis on security are decisive arguments for compliance-conscious organizations.

Advanced features and innovation in Claude 4.5

Beyond the milestones already mentioned, Claude 4.5 introduces a series of substantial improvements that deserve to be detailed. The Skywork AI post, which summarizes Anthropic’s communication, points out that Sonnet 4.5 is currently the company’s best coding model, thanks to top results in OSWorld tests and increased reliability on “real programming benchmarks”. This performance is due to several innovations:

• Prolonged reflection mode: the model can allocate a large token budget to a single task and maintain structured reasoning over the course of several queries. This mode can be activated via the API and improves the quality of solutions for complex problems such as debugging or multi-step planning. On the other hand, it consumes more tokens, so it’s advisable to use prompt and batch caching techniques to keep costs down.
• Memory and context editing: Claude 4.5 adds a context editing function that lets you insert, modify or delete information in the model’s memory without resetting the conversation. This feature simplifies the management of long projects and collaboration between several participants. It is accompanied by a memory tool in the API, which saves relevant fragments and re-injects them during subsequent requests.
• Agent SDK and IDE integrations: Anthropic provides an agent building library (Agent SDK) and native integrations with development environments (terminal and IDE). Developers can create custom agents that use the power of Claude to orchestrate tasks (search, execute commands, call external services) and control a terminal or code editor. Use of the SDK agent consumes API tokens and requires monitoring (unit tests, manual verification) to guarantee the safety of actions.
• Reinforced alignment (ASL-3): Anthropic puts the emphasis on safeguards and announces that Claude 4.5 benefits from ASL-3 (Alignment Specification Level 3). Defenses against prompt injection attacks and risk category management have been strengthened. This results in more frequent refusals of sensitive requests, but ensures greater compliance with regulatory requirements.
• Extended context window: the model manages a standard window of 200,000 tokens, but the extended thinking option multiplies this budget to maintain a thread of thought on long tasks. The official notes indicate thatcontext editing and extended thinking can be combined; however, the use of tools (automatic rather than forced selection) must be adapted to avoid incompatibilities.
• Flexible pricing: according to Skywork AI, the entry price remains $3 per million tokens in and $15 per million tokens out. These rates vary from provider to provider (AWS Bedrock, Google Vertex AI) and can be adjusted according to context (Long context or SDK agent). Users should therefore monitor their consumption and choose the level (Haiku 3.5, Sonnet 4.5) best suited to their use case.

Tips for use and adoption

To take full advantage of Claude 4.5’s capabilities, the editor recommends defining targeted use cases and starting with pilot projects. Best practices include :

1. Define a token budget: extended thinking requires more resources. Setting a token ceiling and caching prompts keeps costs under control.
2. Keep the user in the loop: even if the model can generate code and orchestrate actions, the human must validate modifications and run tests before deployment. This reduces the risk of errors.
3. Choose the right model level: for fast tasks (classification, extraction), the Haiku 3.5 variant is more economical and responsive; for complex reasoning tasks (code auditing, scientific research), Sonnet 4.5 is recommended.
4. Configuring tools: the combined use of reflective mode and tools means that you must let the model decide on the best tool (tool_choice = auto). Forcing a particular tool may result in failure.
5. Establish safeguards: defining permissions and logging decisions makes it possible to trace and audit the agent’s actions, especially when generating sensitive code.

Impact on collaboration and the ecosystem

The arrival of Claude 4.5 is having a significant impact on the developer and enterprise ecosystem. On the one hand, integration into platforms such as GitHub Copilot and AWS Bedrock offers easy access to enterprises and encourages adoption. On the other hand, the ability to combine long memory, external tooling and reflective mode enables the creation of autonomous agents that perform business tasks: troubleshooting legacy code, auditing an infrastructure, generating documentation or writing a report. The experts recommend, however, that teams be trained to write effective prompts and monitor results, as AI is no substitute for human expertise.

Finally, competition between Anthropic, OpenAI and Google is driving innovation: while Claude 4.5 improves depth of thought and security, the other players are focusing on increasing context (Gemini 1.5 offers over a million tokens) and integrating third-party tools. This race is stimulating the emergence ofautonomous agents capable of planning and executing complex actions to boost productivity.