Building AI agents? These 334 models support function calling and are ranked by their agentic capability coverage - tool use, reasoning, JSON output, streaming, vision, and web search.
The foundation of agentic AI. Models must be able to decide when and how to call external tools - APIs, databases, file systems, web browsers. Without this, agents can only produce text, not take action.
JSON Mode (Highly Recommended)
Agents need to produce structured, parseable output reliably. JSON mode ensures the model always returns valid JSON, preventing the parsing errors that break automated workflows.
Reasoning (For Complex Tasks)
Chain-of-thought reasoning helps agents plan multi-step sequences, recover from errors, and make better decisions about which tools to use. Critical for complex autonomous workflows.
Streaming (For Real-Time UX)
Streaming lets you observe agent actions in real-time - see which tools it's calling, watch it reason through problems, and intervene early if it goes off track. Essential for interactive agent interfaces.
Vision (For Multimodal Agents)
Vision-capable agents can process screenshots, analyze charts, read documents, and interact with visual interfaces. Required for browser automation, document processing, and GUI agents.
Web Search (For Research Agents)
Built-in web search lets agents find current information without custom search tool integrations. Ideal for research agents, fact-checkers, and competitive analysis workflows.
Agent-capable models need strong function calling (tool use), reasoning ability, long context windows, and reliable instruction following. They must decide when to use tools, handle multi-step plans, and recover from errors.
GPT-4o, Claude 3.5 Sonnet, and Gemini 2.0 are the top choices for AI agents. They offer reliable function calling, strong reasoning, and the ability to maintain context across long multi-step workflows.
Chatbots respond to individual messages. AI agents autonomously execute multi-step tasks - browsing the web, writing code, calling APIs, and making decisions. Agents use tool calling and planning capabilities that go beyond simple conversation.
Best AI Models for Building Agents (2026) | LM Market Cap