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

Annotations already declare readOnly/idempotent/non-destructive, so the bar is lower. The description adds real behavioral context beyond them: what data is excluded (hidden lists, contact details), that it works for guests, and that it exposes names only. It does not describe pagination or the compare-mode result shape.

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?

Four short, front-loaded sentences with no filler; the dual-mode purpose leads. The trailing 'Read-only' is redundant with the readOnlyHint annotation and is the only wasted clause.

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?

No output schema exists, so the description should ideally explain return values and the pagination ('after') behavior, which it omits. It covers purpose and data scope well but leaves the mechanics for a 3-parameter, 0%-coverage tool incomplete.

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 description coverage is 0%, so the description carries the full burden, yet it never explains event_id, the 'after' cursor, or compare_event_ids. The compare mode loosely implies compare_event_ids, but 'after' and the required event_id are undocumented anywhere.

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?

States a specific verb+resource ('Read guest-visible attendee names') and adds a second mode ('compare accessible event lists to find shared attendees'). The scope qualifiers ('guest-visible', 'hidden lists and contact details are excluded') implicitly distinguish it from list_guests/list_event_staff, though it never names those siblings explicitly.

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?

It describes two usage modes (read vs compare) which implies when to use it, but gives no explicit when-not guidance and names no alternative tools. The agent must infer that list_guests is the fuller-list counterpart.

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