Tool Use
AI Agents
Tool use, also called function calling, lets an AI model ask an app to run a predefined action, like checking a calendar, through a structured request.
Model Context Protocol (MCP) is an open standard that gives AI applications a common way to connect to outside tools and data sources. A system such as a file store, customer database (CRM), or calendar is made available through an “MCP server,” and an AI app that supports MCP can generally connect to it without a custom integration built just for that app. Anthropic introduced it in November 2024. People often compare it to a universal adapter.
Imagine a small interior design studio that tracks client projects in a project management tool and keeps floor plans, mood boards, and supplier quotes in shared file storage. Both tools offer MCP servers, so the studio connects them to its AI assistant.
Now a designer can ask, “Which tasks on the Harper kitchen project are overdue, and where is the latest tile quote?” The assistant checks the project tool, finds the quote in storage, and drafts a short status update for the client. The studio connects the file storage with a read-only account and, using a setting its assistant offers, requires a designer’s approval before any task changes. If the studio later switches AI assistants, it can often reconnect the same servers rather than start over, after checking that the new assistant supports them.
MCP has two sides. The host is the AI app you use, such as a chat assistant or a coding tool. An MCP server is a program that sits in front of a system, such as a shared drive, CRM, or calendar, and describes what that system offers in a standard format the host understands.
A server can offer three main kinds of things:
When you ask a question, the app shares the list of available tools with the AI model, which decides whether to call one. The app may ask you to approve the call first. The server then carries out the request, gets the answer from the underlying system, and sends the result back. Servers can run on your own computer or be hosted online by a vendor.
These ideas are often mixed up, but they sit at different layers.
In practice they work together: an MCP server describes its tools, and the model uses its tool-use ability to call them. Before MCP, AI products typically relied on their own connectors or plugin formats, so the same integration was often rebuilt for each product. With a common standard, one server can work with many AI apps. MCP does not replace APIs, and it does not make a model smarter. It makes connecting a model to your systems more consistent.
Anthropic created MCP, then in December 2025 handed it to the Agentic AI Foundation, part of the nonprofit Linux Foundation, so the standard is no longer run by a single company. Other major AI companies, including OpenAI, Google, and Microsoft, have also announced support for it. Many software vendors now publish MCP servers for their products, and many AI assistants and developer tools can connect to them, often under labels like “connectors,” “apps,” or “integrations.”
For a business, that can mean:
Support still varies by product, and not every app or server offers every feature, so check what a specific tool supports before you plan around it.
Connecting an AI app to your systems gives it real reach, so treat each MCP server like any software you grant access to.
These steps fit within the broader AI guardrails an organization sets for how AI tools may use business data.
SN3 AI Employees are role-trained AI systems deployed inside the tools your team already uses, with guardrails and support after launch.
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