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

Annotations already declare readOnlyHint=true, openWorldHint=true and destructiveHint=false, so safety is covered. The description adds real context beyond that: the return payload is a list of intervals with enumerated statuses, and 'One request per product' warns that a 5-product call fans out into N requests, which matters for latency/rate awareness. It omits the time window the calendar covers, which is the one behavioral gap.

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 tightly packed sentences: the payload shape first, then the request-count/endpoint fact. No filler, and the most decision-relevant information (what comes back, and the 5-product cost) is front-loaded.

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 and no annotations about returns, the description does responsibly describe the returned interval objects and status enum. But it leaves open what date range the calendar spans, how start/end are formatted, and whether intervals are contiguous — details an agent needs to interpret the result. Adequate, not complete.

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 description coverage is 100%, so both parameters are already documented (UUID pattern, 1-5 count, enum default TENTATIVE). The description reinforces the 5-product limit but does not explain show_pending_as, e.g. how choosing CONFIRMED or CANCELLED reshapes the returned statuses. Baseline 3 is appropriate given the schema carries the burden.

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 (availability calendar) plus the exact result shape: per-product interval lists of {start, end, status} with five possible status values. That interval/status vocabulary clearly separates it from sibling calendar and listing tools such as list_calendar_events or get_product.

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 'up to 5 products' framing and the availability-status vocabulary, so an agent can infer this is for checking whether products can be booked. However, it never says when not to use it, nor does it point to a sibling for other availability needs; no exclusions or alternatives are given.

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