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

Beyond readOnlyHint=true the description discloses what the agent would otherwise have to discover empirically: that buy_url deep-links into Mindbody's cart, that passes are valid across all four studios, that contracts auto-renew so minimum_term_months must be quoted with the price, and that a variable-amount gift card is always returned alongside offers. These are non-obvious output and framing behaviors, not restatements of the annotations.

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?

Front-loaded with the resource and the return shape, then usage trigger, then caveats in descending importance. Slightly dense with three separate caveats packed into the back half, but each sentence carries operational information an agent needs.

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 still tells the agent what comes back (price in euro, buy_url, an auto-renewing contract with minimum_term_months, a companion gift card). Combined with a fully documented three-parameter schema and read-only annotations, nothing material is missing for correct invocation.

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% and both enums are documented in the schema, so the baseline applies. The description adds adjacent meaning (passes work at all four studios, gift card is a separate companion record) but contributes no filter-specific syntax or interplay guidance such as how new_students_only combines with category.

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 opening sentence names the exact resource set (class passes, intro offers, memberships) and states what each record carries (euro price plus a buy_url), which cleanly separates it from schedule/classes/teachers siblings. An agent can identify this as the pricing-and-purchase tool without opening the schema.

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?

"Use this for anything about what something costs or how to buy it" gives a clear positive trigger, and the gift-card sentence redirects the buy-for-someone-else case. It stops short of naming a specific sibling tool or stating an explicit when-not-to-use condition.

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