# Function Calling

> The ability of AI models to identify when a conversation requires calling an external function or API, and to generate the structured parameters needed to make that call.

Category: Architecture

Source: https://chipp.ai/ai/glossary/function-calling

Function calling (also called tool use) is the ability of AI models to determine when a user's request requires calling an external function or API, and to generate the structured parameters needed to make that call. It bridges the gap between AI conversation and real-world actions.

How function calling works: the AI model is given descriptions of available functions (name, description, parameters), during conversation the model decides when a function should be called, the model generates structured JSON parameters for the function call, the application executes the function and returns the result, and the model incorporates the result into its response.

For example, if a user asks "What's the weather in New York?", the model recognizes this needs real-time data, generates a function call like getWeather({location: "New York"}), receives the weather data, and responds naturally: "It's currently 72F and sunny in New York."

In AI agents, function calling enables: appointment booking (calling a calendar API), CRM updates (creating leads in HubSpot), data retrieval (looking up order status), payment processing (initiating transactions), email sending (triggering messages), and any other API-powered action.

On platforms like Chipp, function calling is exposed through "Custom Actions" and "Pro Actions (MCP)" — visual builders that let non-developers define what external functions their AI agent can call, when to call them, and what parameters to pass. The AI decides during conversation when to use these tools based on the user's needs.

## Related Terms

- [API](https://chipp.ai/ai/glossary/api.md): Application Programming Interface — a set of rules allowing different software applications to communicate and exchange data.
- [AI Agents](https://chipp.ai/ai/glossary/ai-agents.md): Autonomous AI systems that can perceive their environment, make decisions, and take actions to achieve specific goals.
- [Model Context Protocol (MCP)](https://chipp.ai/ai/glossary/mcp-protocol.md): An open protocol standardizing how AI assistants connect to external data sources and tools through a universal interface.
- [AI Orchestration](https://chipp.ai/ai/glossary/ai-orchestration.md): The coordination of multiple AI models, tools, and workflows to accomplish complex tasks that require multiple steps and capabilities.

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This term is part of the [Chipp AI Glossary](https://chipp.ai/ai/glossary), a reference of AI concepts written for builders and businesses.

Build AI agents with no code at https://chipp.ai.