What this is
Tool use existed before anyone named a standard. Each company built its own wiring: this model talks to this calendar in this special way. Four tools and three models meant a lot of custom integrations.
MCP is an agreement about the shape of the plug. If the calendar, the files, and the database offer the same kind of socket, a program that speaks that shape can attach to any of them. The connector is built once. Other models can use it. MCP is a protocol, not a product.
Pre-standard tool use was N×M integration work. Each model client spoke a vendor-specific function-calling schema; each application exposed its own interface.
The Model Context Protocol is an open standard for how clients discover and call tools and data sources. It separates tool servers from model hosts. The capability remains tool use; MCP is the transport and schema that make that capability portable.
Easy to mix up
This is easy to mix up with a new kind of intelligence. Standardizing the plug does not add a capability the model lacked. It lowers the cost of attaching tools that already exist.
It is also easy to mix up with a safety story. The plug does not decide read versus write. What a tool is allowed to do is set by the server and the policy around it.
Standardizing the connector does not add capability the model lacked. It lowers the cost of attaching tools that already exist.
MCP does not settle authorization, least privilege, or whether a tool is read-only. Those are properties of the server and of policy. Portability is not safety.
From work
A team wraps the company calendar as an MCP server so two different chat products can ask for free/busy without two custom integrations. That is the whole win: one connector, two clients.
If that server also exposes “create event,” both clients inherit a write. The standard did not make the write careful. It made the write reusable.
An MCP calendar server that exposes list-events and create-event will present both tools to every compliant host. Reuse cuts integration cost and multiplies the blast radius of a write.
Review the tool list on the server, not the protocol name on the slide.
What to ask next time
Is MCP the plug, or is the word being used for the tools themselves? Which tools does this server actually expose, and which of those write?
Ask whether MCP is the transport or a stand-in for “connected.” Then ask for the server’s tool list and the authorization on each.