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

Annotations already declare readOnlyHint=true, idempotentHint=true, destructiveHint=false and openWorldHint=false, so the description adds nothing on the safety profile. Worse, "tracker" suggests stateful accumulation of a guest list while the annotations declare a pure read with no side effects, leaving the agent unsure what actually happens to the supplied array.

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 words is technically concise, but this is under-specification rather than economy — there is no front-loaded statement of action or scope for the agent to act on.

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?

There is no output schema, so the description must carry the load of explaining what the tool returns or does with the guest array, and it does not. With a nested object parameter, an enum-driven status field, and semantics that conflict with readOnlyHint, the definition is far too thin to call correctly.

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%, and the sole required parameter `guests` is an array of objects with a status enum (invited/yes/no/maybe) and an optional plusOne. The description's phrase "guest list" only loosely gestures at the `guests` parameter and explains nothing about the status values or plusOne.

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?

"Guest list tracker" is a noun phrase that essentially restates the title "Planning Guest List"; it names no verb and does not say whether the tool reads, validates, summarizes, or stores a guest list. It gives no signal distinguishing it from siblings like planning_event_checklist or planning_event_budget.

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?

There is no guidance at all on when to use this tool, no prerequisites, and no named alternative among the many planning_* siblings. The only implied usage comes from the word "guest", which is inference rather than instruction.

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