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

Beyond the annotations (readOnly, idempotent, non-destructive, closed-world), the description discloses the key behavioral trait: it 'opens nothing by itself' and only returns instructions. That is exactly the context needed to prevent an agent from assuming a booking was made. It could say more about how the step list is scoped or whether it reflects current availability.

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?

The core message is front-loaded, but the API aside with a 'checked 28 Oct 2026' date adds bulk without helping an agent decide or act, and the sentence structure is dense with parentheticals. Trimming to the effect, the follow-up tool, and the constraint would read better.

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 parameters and no output schema, the description carries the full burden of explaining what comes back and how the target class is conveyed, and it only partly does the latter—nothing says whether the class is inferred from conversation history or must be searched first. It is sufficient to avoid misuse but leaves a real gap about inputs.

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?

The tool takes zero parameters and the schema is empty, so there is no parameter meaning to add. Baseline 4 applies; if anything the description could explain how the target class is identified given no inputs.

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 names a specific verb and resource ('Book class in the user's own ClassPass account') but immediately redefines the deliverable as step-by-step instructions ('screens, buttons, fields') rather than an actual booking. An agent can still understand what it gets back, though the headline verb oversells the effect.

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 states the workflow explicitly: call this to get steps, then perform the booking with the cotlet_browser_* tools in the user's ClassPass Cloud Browser. It also explains why the official ClassPass Inventory API is not an option (approved partners only). It stops short of saying when NOT to use it versus siblings like classpass_search_classes or cotlet_app_guide.

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