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

Annotations only establish that this is a non-destructive, closed-world read. The description adds substantial behavioral context beyond that: 21-day max range, Mon–Fri 10:00–18:00 Lisbon time, closure on Portuguese public holidays, and a 24-hour booking lead time. It does not mention rate limits, but the coverage is well above the annotation baseline.

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?

Two dense sentences with zero filler; the core purpose is front-loaded and the constraints and return format follow in a logical order. Every clause earns its place.

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 states the return format ('ISO 8601 with the Lisbon offset') in addition to the availability rules. Nothing an agent needs to invoke this correctly appears to be 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 the package enum is documented in detail in the schema, so the schema carries parameter meaning. The description adds only one extra constraint, the 21-day maximum span between from_date and to_date, which is useful but marginal beyond the schema baseline.

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?

Specific verb+resource: 'Lists free start times at Estúdio 266 for a bookable package between two dates.' Scope and subject are unambiguous, and it is clearly the availability-query sibling of request_studio_booking / reschedule_studio_booking rather than a booking mutation.

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?

The description implies usage (checking availability for a package before booking) and supplies the operating constraints, but it never explicitly states when to call this versus request_studio_booking or the other siblings. Guidance is implied rather than stated.

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