Practical MCP with FastMCP & LangChain

Tools (Server Side)

Tools are the action layer of MCP. They represent operations that a server makes available for execution. Unlike other features, tools run logic. They can create, modify, or trigger something outside the conversation. In many cases, they affect real systems.

A tool might open a support ticket, send a message to Slack, generate an invoice, update a customer record, trigger a CI pipeline, or call a third-party API. Because tools can change state or initiate workflows, they are the most powerful and potentially risky features in MCP.