How does an AI agent use tools like my email or my business system?
The short answer
The model itself cannot open anything. It can only ask. When it needs data or an action, it writes a structured request; your software receives it, carries it out, and hands back the result. So what an agent can do in your company is decided by the tools you give it, not by the model.
The model asks; your software acts
A language model produces text, nothing more. It cannot open your mailbox or post an invoice by itself.
What makes an agent possible is a simple arrangement. You describe to the model a list of tools. Each tool has a name, a short description of what it does, and the details it needs. For example: “find the open invoices of a client; needs the client’s name”. When the model decides it needs a tool, it does not run it. It writes a request: “use this tool, with these details”.
Anthropic’s documentation is explicit about this: the model never runs anything on its own. Software outside the model, usually yours, runs the operation, and the result goes back to the model. The model reads the result, then decides the next step: answer, or ask for another tool. This loop repeats until the work is done.
A common plug for tools
Connecting every AI application to every company system, one by one, is slow and expensive. In November 2024 Anthropic introduced the Model Context Protocol, usually called MCP: an open standard for connecting AI assistants to the systems where data lives. A system connected once through MCP can be used by any AI application that supports the standard. Think of it as a common plug shape: build the socket once, and many devices fit it.
The tool list is your permission list
This is the point that matters for a leader. An agent can do only what its tools allow. So the list of tools is the list of permissions you are giving it.
- Read before write. Start with tools that only read: search, look up, summarise. Add tools that change things only when you trust the results.
- Narrow tools are safer than broad ones. “Read this client’s invoices” is safer than “run any query on the database”.
- Approval for actions that matter. OWASP, a well-known security community, lists “excessive agency” among the main risks of AI applications: an agent given more functions, permissions or independence than it needs. Its advice includes requiring a person to approve high-impact actions before they happen.
The question Can an AI agent safely read my company’s ERP system? applies this to your main business system.