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

Annotations already cover readOnlyHint and openWorldHint, and the description adds genuinely new behavioral facts beyond them: no authentication is required, each request spans at most 14 days, and returned times use the location's own time zone. It does not describe pagination or response shape, which keeps it short of a 5.

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 short sentences, front-loaded with what the tool returns, followed by the two constraints an agent would trip over. No filler or restatement of the name.

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?

For a read-only availability query with a fully documented eight-parameter schema and no output schema, the description covers the essentials: scope, request-size limit, auth posture, and time-zone interpretation of results. Only the response structure ('day by day') is left slightly vague.

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%, so all eight parameters are already documented in the schema, including the 14-day bound on `until` and the source of the ids. The description restates the one-service/one-location constraint and the time-zone semantics but adds no per-parameter meaning the schema lacks, so the baseline of 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 resource and scope: free/available times for exactly one service at one location, returned day by day. That cleanly separates it from get_business and prepare_booking, but the description never names or contrasts those siblings explicitly, so differentiation is inferential rather than stated.

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?

'Needs no sign-in' and the 14-day cap give real operational context for when this call is usable, and the 'as the booking page offers them' framing implies it is the availability lookup that precedes prepare_booking. However, there is no explicit when-to-use or when-not-to-use guidance and no alternative named.

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