MCP prompts: reusable invocation templates

MCP prompts are reusable templates a server exposes so a client can present structured invocation patterns to a user. A client lists prompts with prompts/list and retrieves one with prompts/get, supplying arguments that fill the template. Prompt support is client-specific.

A server may expose templates that package a set of argument-driven instructions. The client lists them and can present each to the user as a suggested start to a task. Whether a client surfaces prompts as first-class UI is up to the client.

A prompt template declares the arguments it accepts. The client prompts the user for values and fills them in, turning the template into concrete working instructions.

A prompt is input to a model — guidance the client hands to a user or model to structure a response. A tool is an executable action. The distinction matters for how the client models each, though both are declared and negotiated through the protocol.