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

Annotations already declare read-only, idempotent, non-destructive, closed-world, but the description adds real value beyond them: no hold, no charge, no contact, where the operator's card and cancellation rules apply, and exactly what the error response contains. That is precisely the context an agent needs before promising a user a booking.

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?

Three tight sentences, front-loaded with the core behavior, then the non-effects, then the failure mode — no filler and nothing repeated from the schema or annotations.

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 so: a URL to the operator's booking page with fields pre-filled, or an error enumerating open times. Nothing an agent needs to call this correctly or set user expectations is missing.

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 coverage is 100% and each param already documents its format and source (service_id from list_services, start_time from list_availability). The description only restates that the three values are filled into the link and that a bad time yields an error with that day's open times, which is marginal added meaning. 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 a specific verb and resource: checks availability for a service/date/start time and returns a joinmane.com booking link pre-filled with those values. It implicitly separates itself from list_availability (raw times) and list_services (IDs) by describing the check-and-link outcome rather than a listing.

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?

Clearly frames the boundary: 'It does not book, hold the time, charge or contact anyone' and explains the booking only completes when the client confirms on joinmane.com. The failure case ('result is an error listing the open times that day') is spelled out, though it never explicitly says to call list_availability first or when to prefer this over the sibling tools.

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