Building Agents with Claude: Tools, Reasoning, and the MCP Standard

If you are new to the AI space, the term 'agent' can sound intimidating. In reality, an AI agent is simply a language model running in a loop, equipped with tools it can use to interact with external systems. While other companies are building agents deeply tied to their specific data platforms or operating systems, Anthropic takes a model-first approach. They provide Claude, a highly capable reasoning engine, alongside the open-source plumbing needed to connect it to the real world. The Claude Agent Ecosystem There is no single boxed product called a "Claude Agent." Building an agent with Anthropic means assembling several distinct parts: The Core Model: Claude serves as the reasoning engine. It is known for its massive context window and safety-focused training. Tool Use: The API allows Claude to call external functions, allowing it to fetch live data or trigger actions. Model Context Protocol (MCP): An open standard created by Anthropic that standardizes how AI models connect to data sources and tools. The Agent SDK: A framework that handles the complex logic of planning tasks, managing files, and running the agent loop. Claude Code: A practical, real-world example of the Agent SDK in action, designed to work as an autonomous coding assistant inside your terminal. Computer Use: An experimental feature where the model can view screen captures and control a mouse and keyboard to operate standard software. flowchart TD C[Claude Model] --> T[Tool Use API] T --> MCP[Model Context Protocol] MCP --> SDK[Claude Agent SDK] SDK --> CC[Claude Code] C --> CU[Computer Use] Core Components Reasoning and Long Context Claude's primary strengths for agent workflows are its ability to ingest massive amounts of text and its careful approach to problem-solving. Anthropic trains its models using a framework that prioritizes harmless and honest behavior. In an agent context, a model that pauses to ask for clarification is vastly superior to one that confidently executes the wrong acti