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

Annotations already declare readOnlyHint and destructiveHint=false, so the closing "Read only: nothing changes and no message is sent" mostly reinforces structured data. The description still adds genuine behavior beyond annotations: nearest-first ordering, the exclusion of students with no birth date, and how age is expressed via "turns".

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?

The window size is front-loaded and every clause carries information, including the field list and the guardian-phone caveat. The single long sentence with stacked parentheticals is dense but not padded.

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, and the description compensates by enumerating the returned fields (name, birthday as next date, turns, days_until, phone, app_url). Combined with the exclusion rule and ordering, an agent has everything needed to call it and interpret results.

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%, and the description's "default 7, up to 60" merely restates the schema's default and maximum. It adds no new syntax or interpretation for the days parameter (e.g., whether 0 means today only), so the baseline 3 applies.

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?

The description names a precise verb and resource — active students with a birthday today or within N days — plus the ordering and returned fields. That is clearly distinguishable from siblings like list_students or list_inactive_students, which serve roster rather than birthday lookups.

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 gives an explicit triggering question ("who has a birthday this week?") and the trainer's downstream action (congratulate, then get_student for details). What is missing is an explicit when-not clause or a named alternative for full-roster lookups, which is left to inference.

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