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

Annotations already declare readOnlyHint=true, destructiveHint=false and openWorldHint=false, so safety is covered. The description's wording 'contact the advertiser' is ambiguous — it could be read as sending outreach (a write) rather than returning contact details, which sits uneasily with readOnlyHint even if not an outright contradiction. It adds the precondition on prior results but nothing about return contents or limits.

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?

One sentence, front-loaded with the usage condition and free of filler. Slightly compressed to the point that the actual output is never stated, but nothing is wasted.

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?

The tool is simple (one required param) and an output schema exists, so return values needn't be described. The agent gets both the trigger and the precondition. The remaining gap is the ambiguity over whether 'contact the advertiser' means retrieving details or initiating contact.

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 `id` parameter is fully documented as a listingKey from search_properties or get_property. The description only reinforces the provenance of the id, adding no syntax or constraint detail beyond the schema. Baseline 3 is appropriate when the schema does the heavy lifting.

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 implies the tool surfaces advertiser contact details or a link to the original listing, but it never states a verb+resource outcome (e.g., 'Returns the advertiser's contact info and original listing URL'). The agent must infer the return from the trigger phrasing, and there is no differentiation from get_property beyond the 'contact' framing.

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?

It gives an explicit trigger: only when the user 'explicitly' asks to contact the advertiser or open the original listing. It also states the precondition that the property must have been previously returned by PropFácil. It stops short of naming alternatives (e.g., use get_property for full details) or stating when not to use it.

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