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

Annotations already declare readOnlyHint, openWorldHint and destructiveHint=false, so safety is covered. The description adds real behavioral context: availability is volatile ("a listing can sell at any time") and a human specialist is authoritative, which tells the agent how much to trust the result.

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, no filler, with the core capability stated first and the usage cue and trust caveat following in priority order. Nothing could be removed without losing 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?

For a one-parameter read tool with full schema coverage and no output schema, the description covers what is checked, when to call it, and how reliable the answer is. Only the shape of the per-id result is left implicit, which is a minor gap for such a simple check.

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 single parameter already documents "Listing ids from search_watches" plus a 24-item cap. The description's phrase "a watch from earlier" reinforces the source of the ids but adds no syntax or batching detail beyond the schema, so the baseline 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?

The description names a specific verb and resource — reporting whether listings are still on watchesinstock.com — which is distinct from lookup siblings like get_watch or price_check. It does not explicitly name a sibling, but the operation (a liveness check on previously seen listings) is 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?

"Use it when someone asks if a watch from earlier is still there" gives a clear triggering condition tied to previously returned listings. It stops short of naming an explicit alternative, though the closing line about a specialist implies get_specialist_link is the escalation path.

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