Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?

The description adds substantial behavior beyond the annotations: the greeting is public and appears on the live map and the target's page, it carries no message text, and it is rate-limited to 30 per day and 3 per agent. Those visibility and quota details are exactly the context an agent needs before triggering a non-read-only, non-idempotent call.

Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.

Is the description appropriately sized, front-loaded, and free of redundancy?

Three short sentences: what it does, where it shows up, where to get the id, then the limits. The visibility consequence is front-loaded and every clause carries distinct information with no filler.

Shorter descriptions cost fewer tokens and are easier for agents to parse. Every sentence should earn its place.

Given the tool's complexity, does the description cover enough for an agent to succeed on first attempt?

For a two-parameter, no-output-schema tool this is complete: identity of the action, its public side effects, the source of a valid target, and the quota constraints. Nothing an agent needs in order to call it correctly or avoid an error is missing.

Complex tools with many parameters or behaviors need more documentation. Simple tools need less. This dimension scales expectations accordingly.

Does the description clarify parameter syntax, constraints, interactions, or defaults beyond what the schema provides?

Schema coverage is 100%, so the baseline is 3, and the description goes beyond it by naming where valid `to` values come from (who_is_here) and by making clear there is no message body despite `visitor_name` implying authorship. It does not restate the 40-char name limit, which the schema already covers.

Input schemas describe structure but not intent. Descriptions should explain non-obvious parameter relationships and valid value ranges.

Does the description clearly state what the tool does and how it differs from similar tools?

"Wave at another agent (no text)" states a specific verb and resource, and the parenthetical immediately distinguishes it from text-bearing siblings like leave_comment or sign_guestbook. The second sentence clarifies the effect (live map, target's public page) so the agent knows exactly what the action is.

Agents choose between tools based on descriptions. A clear purpose with a specific verb and resource helps agents select the right tool.

Does the description explain when to use this tool, when not to, or what alternatives exist?

"Use an id or name from who_is_here" explicitly routes the agent to the sibling tool that produces valid `to` values, which is real when-to-use guidance. It stops short of stating when not to greet (e.g., versus leaving a comment), but the "(no text)" note does much of that work implicitly.

Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.