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

Annotations already declare readOnlyHint, idempotentHint and openWorldHint=false, so the safety profile is covered. The description adds currency (EUR) and the presence of per-offer sign-up links, which is useful but modest; it says nothing about how many offers come back, pagination, or behavior for an unknown/foreign gym id.

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 front-loaded phrase with no filler; every element (offer types, currency, sign-up link) earns its place and nothing is repeated from the schema.

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 describe the payload's content and key attribute (prices in EUR, sign-up link per offer). It stops short of indicating structure or size of the returned offer list, but is otherwise sufficient for a 2-parameter read tool.

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%: `gym` is documented as the slug/Gymmy id from search_gyms and `locale` documents the fr/en answer language with default fr. The description adds nothing about parameters, 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?

States the concrete resource it returns (memberships, class packs, trial offers) with two distinguishing details: prices are in EUR and each offer carries a sign-up link. It's clearly distinct from sibling reads like get_gym or get_schedule, though it never names the verb 'retrieve' or an alternative tool 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?

There is no explicit when-to-use or when-not-to-use statement. Usage is only implied by the mention of a 'direct sign-up link per offer', which suggests it feeds a pre-signup flow (start_trial), but the agent must infer this rather than being told.

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