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

Annotations already cover read-only, idempotent, non-destructive. The description adds genuinely useful domain context beyond them: the free-by-default bookability model and the meaning that returned dates are the exceptions (unavailable / soft_hold / confirmed_booking). This semantic framing is not recoverable from the schema or 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?

Three tight sentences with the core scope front-loaded, followed by the model explanation and the window limits. No filler; every sentence carries distinct information.

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 it does so by naming the categories of marked dates the tool returns. Slightly short of a 5 because it doesn't describe the response shape (fields per marked date), but the semantics are clear enough to call correctly.

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 schema already documents both dates, their YYYY-MM-DD format, the 90-day default and 365 cap. The description merely restates the same defaults and caps, adding no new syntax or format detail beyond the schema.

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 precise verb+resource combination ('The member's OWN availability for a date window'). The capitalized 'OWN' implicitly contrasts with sibling tools like check_member_availability, letting an agent distinguish them without opening schemas.

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?

Usage is implied by the 'OWN' framing and the free-by-default explanation, but no alternative is named explicitly (e.g. 'use check_member_availability for another member'). The agent must infer when this tool is the right pick versus the other availability siblings.

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