Tool manifest / tool definition
Also called: tool description, tool schema
The name, description, and input schema an MCP server publishes for each tool, which the model reads to decide when and how to call it.
When a client connects to a server, the server returns a list of its tools. Each entry has a machine name, a natural-language description, and a JSON Schema for its arguments. The description is not documentation for humans — it is instructions to the model about what the tool does and when to use it, and it is injected into the model's context.
Why it matters
Because the description reaches the model as trusted-looking text, a server author (or an attacker who controls a server) can put anything there: hidden instructions, requests to pass along secrets, directions to call other tools. The model may follow them before any tool is ever invoked. Tool descriptions are the single most abused surface in MCP security research to date.
Exposure map
Live counts of instances showing this pattern will appear here once the exposure map is collecting data.