An MCP server is a program that exposes tools, data, and actions to AI agents over the Model Context Protocol (MCP), an open standard introduced by Anthropic. It lets an assistant like Claude, or any MCP-capable client, call real functions and fetch live data mid-conversation instead of relying only on what it was trained on.
Language models are powerful but sealed off from live systems: they cannot natively query your database or a government registry. MCP is the connector standard that fixes this. An MCP server advertises a set of tools with typed inputs and outputs, and the agent calls them as needed, so the model reasons while the server supplies ground-truth data and side effects.
A REST API is called by code a developer writes. An MCP server is called by the AI agent itself, which reads the tool descriptions and decides when to use them. The same underlying data can be offered both ways: REST for your application code, MCP for the assistant. That is how a user can ask a question in plain language and have the agent pull the records to answer it.
Related on Amalgament: Amalgament MCP server · API documentation
Any MCP-capable client, including Claude, and a growing list of tools like Cursor and other agent frameworks. Because MCP is an open standard, one server works across all of them.
To build one, yes. To use one, no. Connecting an existing MCP server to an assistant is usually a couple of lines of configuration, after which you interact with it in plain language.
More terms: KYB (Know Your Business) · UCC filing (UCC-1) · APN (Assessor's Parcel Number) · Entity resolution · Business registry (Secretary of State filing) · UEI and SAM.gov · Non-FCRA (business-purpose) data · Context layer (for AI)