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

Annotations already declare readOnly/idempotent/non-destructive/closed-world, so the safety profile is covered. The description adds real behavior beyond that: a fixed 14-day horizon and a booking link with the class pre-picked, which tells the agent what it can do with the result. It stops short of noting rate limits or handling of invalid gym ids.

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?

One dense sentence that front-loads scope and then the payload; every clause carries information (horizon, fields, pre-picked booking link). Nothing is padded or restated from the title.

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 correctly takes on the job of describing the return payload, which it does well. It is slightly incomplete on edge behavior (empty schedule, out-of-window date, default locale), but an agent has enough to call it 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 100%, so the schema already documents gym, date (YYYY-MM-DD) and locale. The description adds nothing about the date window's interaction (e.g., must fall inside the 14 days) or the locale default, so the 3 baseline 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?

States a concrete verb+resource with scope ('Upcoming classes of a Gymmy gym (next 14 days)') and enumerates the returned fields (time, duration, spots left, booking link). It is clearly differentiated from get_gym/get_prices, but never explicitly contrasts itself with the sibling my_schedule, which is the closest alternative.

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?

Usage is only implied: an agent can infer 'use this to browse a specific gym's schedule', but there is no when-to-use vs when-to-use-something-else guidance, and no mention of my_schedule despite it being the obvious overlapping sibling. No exclusions or prerequisites are stated.

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