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

Annotations already declare readOnly, idempotent, openWorld and non-destructive, so the safety profile is covered. The description still adds real behavioral detail beyond them: response shape (class object plus list of visits) and the edge case that an invalid LastModifiedDate silently defaults to null rather than erroring. That null-default behavior is exactly the kind of trap an agent needs to know about.

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 alternates between a restated title/endpoint, a stray "Mindbody calls: 1" fragment, the alternative-tool routing, the return description, and a date caveat, with no clear ordering logic. No sentence is harmful, but the header echo and the orphaned call-count note are filler that push the useful routing advice into second position.

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?

With no output schema, the description carries the return-value burden and does so (class object with a list of visits). Combined with full schema coverage and annotations covering the safety profile, an agent has enough to invoke it correctly; only pagination or roster size expectations are unaddressed.

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, but the description earns above baseline by documenting failure-mode semantics the schema omits: an invalid date passed via LastModifiedDate defaults to null instead of raising. It does not clarify classID sourcing or the siteId default, but those are already fully specified in the schema.

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 states a specific verb+resource ("get class visits" / "Returns a list of visits that contain information for a specified class") and explicitly names a sibling it is not (find_likely_attendees). The leading name-plus-endpoint echo ("Get Class Visits — GET /class/classvisits") adds no information beyond the title, but the substantive sentence makes the purpose unambiguous.

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 one explicit routing rule with the selecting condition: if the goal is finding clients likely to book a class, use find_likely_attendees instead, because that tool reads and ranks many rosters in one call. It does not address other closely-related siblings such as class_attendance_summary or attendance_with_revenue, so the when-not coverage is partial rather than complete.

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