Understand MCP through tools, resources, and trust boundaries

Map the participants

The Model Context Protocol documentation describes a host application that manages clients connecting to servers. Servers can expose tools, resources, and prompts. A tool offers an executable capability, a resource supplies contextual data, and a prompt provides a reusable interaction template.

Draw the practical boundary in your own deployment: where the host runs, where each server runs, what credentials are used, and which external services a server can reach. The protocol connection is one part of that broader access path.

Inspect the capability before using it

Read the available descriptions and schemas. Identify the operations that read data, the operations that modify data, and the operations that can trigger external effects. Clear names and narrow input shapes make a capability easier for both people and models to use correctly.

• Purpose: Does the capability serve the task you actually need?
• Inputs: Are identifiers, optional values, and allowed ranges clear?
• Access: Which user or service identity is applied when the operation runs?
• Results: What evidence shows success, failure, or a partial result?

Do not infer compatibility from a server name alone. Check the protocol version, supported transport, and features for the specific client and server versions you plan to use. Preserve that combination in the integration record.

Keep authorization in the execution path

A convincing tool description does not grant permission to access a private record. Enforce access controls where the underlying operation executes, and limit credentials to the relevant task. Treat returned documents and tool output as data that may contain untrusted instructions.

Start with a small set of read operations in an approved environment. Review what information reaches the model and what appears in logs. Expand the capability set when there is a concrete need and a defined way to verify behavior.

Design a useful stop condition for unavailable tools or incomplete context. The application should be able to explain which required operation failed and preserve the work completed before that point.

Continue to agent action boundaries for orchestration design. The security test guide helps turn access assumptions into repeatable checks.