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

Annotations already declare a non-read-only but non-destructive, open-world write. The description adds real context beyond that: the side effect (adds a visit to the member's attendance), the confirmation requirement, and the auth prerequisite (Cotlet API key with app access). It does not address duplicate check-ins, reversibility, or enrollment prerequisites.

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 sentences, front-loaded with the action and its effect, followed by confirmation and auth notes. Slight redundancy between "Record that a member attended" and "Checks one member into one class," but nothing is wasted overall.

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 mutation with annotations and no output schema, the description covers purpose, side effect, confirmation, and credentials adequately. Remaining gaps (what happens if the member is already checked in, whether a check-in can be undone) are edge cases rather than blockers.

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%, with both class_id and person_id documented as coming from list_classes and list_members. The description only restates the one-member/one-class relationship and adds no syntax or format detail beyond the schema, 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 gives a specific verb+resource ("Record that a member attended a class") and clarifies scope: one member into one class, which appends a visit to attendance. It distinguishes itself semantically from siblings like zen-planner_book_class, though it never names an alternative 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 covers the confirmation policy ("By default you confirm each call; you can switch that off") and flags the need to confirm before calls that reach other people. However, it offers no guidance on when to check in versus book_class or cancel_reservation, so selection between siblings 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.