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

readOnlyHint=true already covers the safety profile, so the description's contribution is scoping: it declares the record type (door/desk), the date-range window, and the shape of each row (member, time, method). It omits operational behavior an agent would want — the default limit of 100 / max 500, ordering, and what happens when from/to are omitted.

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?

A single dense sentence with the resource and scope front-loaded and no filler. The parenthetical return-field list is compact and earns its space, though it slightly interrupts the sentence flow.

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 read-only list tool with no output schema, the description does the important work of naming the returned fields and the filter dimensions. The remaining gap — pagination default and behavior when the date range is omitted — is a real but modest omission.

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?

At 60% schema coverage, the description usefully maps "date range" to from/to and "optionally for one member" to userId, which the schema leaves undescribed. It says nothing about limit or the absence of required dates, so the undocumented parameters remain undocumented.

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?

Names a specific resource and scope: gym door/desk check-ins in a date range, with the returned fields (member, time, method) enumerated. It implicitly separates itself from list_checkins (generic coaching check-ins) and check_in_gym_member (a write), but 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?

"At a gym in a date range, optionally for one member" implies when the tool applies, but there is no explicit when-to-use or when-not, and no routing to alternatives such as get_gym_attendance_summary (aggregates) or check_in_gym_member (writes). The agent must infer the boundary from the name and sibling list.

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