Given the tool's complexity, does the description cover enough for an agent to succeed on first attempt?
For a simple one-parameter read-only tool with no output schema, the description covers the essential return data (title, URL, indexed elements). It hints at the indexing scheme (@1, @2) which is useful for later interactions, but it does not explicitly state limitations (e.g., only interactive elements are returned) or prerequisites (e.g., tab must be active). Given the simplicity, the description is nearly complete, but a small gap remains regarding how the snapshot relates to other tools and any constraints on its use.
Complex tools with many parameters or behaviors need more documentation. Simple tools need less. This dimension scales expectations accordingly.