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

The annotations already declare readOnly, idempotent, and non-destructive behavior, and the description adds important non-obvious semantics: availability statuses (free, tentatively held, booked, unknown), the publishing limitation, and the critical rule that unknown means ask, not busy. No contradiction with the annotations is present.

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 description is three short sentences with the core behavior front-loaded. Every clause earns its place: the status query, the publication caveat, the unknown interpretation, and the read-only note. There is no wasted or irrelevant text.

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?

Given 3 parameters, no output schema, and annotations covering safety, the description is sufficiently complete: it names the possible statuses, explains the unknown case, and provides the prerequisite relationship to search_vendors. A response-shape enumeration is not necessary because the meaningful result vocabulary is already disclosed.

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 description adds meaning to vendor_id by tying it to 'id from search_vendors,' which is not in the schema's raw type/format fields. It also reinforces that date is the target date. Locale is the only parameter not mentioned in prose, but the schema already documents its default and language behavior, so the description does not need to repeat it.

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 the exact query: 'Whether one vendor ... is free, tentatively held, or booked on a given date.' It also distinguishes the tool from sibling tools by specifying that the vendor id comes from search_vendors, making the resource and scope unambiguous.

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 gives clear context: the tool is only meaningful for vendors who publish availability, and it explains how to interpret "unknown" (ask them, never busy). It implicitly tells the caller to use it after search_vendors, but it does not explicitly name alternative tools or say when not to use it beyond the publishing caveat.

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