LESSON 178 / 215·2 min readIntermediate

MCP

ReferenceReference guide

Words made simple

A few useful meanings before you read the explanation.

MCP: A shared protocol for connecting AI applications to tools and resources. It does not replace permission checks or application security.
AI: Software techniques for tasks such as recognizing patterns, understanding language or generating content.
Token: A small piece of text processed by a model. It may be a whole word, part of a word, or punctuation.

More words from this lesson

Schema: A description of the fields and value types that data should contain. It helps check that an answer has the expected shape.
Tool calling: The model proposes using a named function and supplies its inputs. Application code checks permissions and runs the function.
Authentication: Checking who a user or service is, such as by verifying a login session.
Authorization: Checking what that identity is allowed to read or do. Being logged in does not grant access to every record.

It standardizes how AI applications connect to and discover external tools and context.
Multiple approved hosts can reuse the same server-side capability contracts rather than each building a custom integration.

Function calling lets a model propose a structured operation.
MCP provides an integration protocol for discovering/invoking capabilities.
The host can turn a model proposal into an MCP request that calls an existing REST service underneath.

I authenticate requests, verify token properties, authorize each tool and object, restrict downstream credentials/egress, validate schemas/results, review tool definitions, and audit actions.
Connection permission does not equal customer-record permission.

The host should not automatically expose or execute it.
Tool descriptions are untrusted unless reviewed; allowlists and execution policy block capabilities outside the task.
I investigate the server/definition change and preserve an audit record.

PAUSE & RECALL