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

Annotations already declare readOnly, idempotent and non-destructive, so the safety profile is covered. The description adds genuinely new behavioral context: contact details are excluded from the payload and the correct action is to redirect the user to the listing URL to contact the advertiser.

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 tight sentences: the core result is front-loaded, followed by input sourcing and then the contact-details caveat. No filler.

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?

An output schema exists, so return values need no explanation, and the description still characterizes the payload. It covers id sourcing and the contact-detail exclusion; only the absence of any sibling routing (fetch vs find_similar_listings vs get_catalog) keeps it short of 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, including the id/URL duality and the locale enum. The description repeats the id sourcing but adds nothing about locale semantics, so baseline 3 is appropriate.

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?

Names a specific verb and resource ('Full details of one listing published on new.estate') and enumerates what it returns (description, photos, features, facts). It is clearly distinguishable from sibling listing tools like search_listings or find_similar_listings.

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?

Tells the agent where the id comes from ('a listing id from search_listings or the URL of a listing page') and sets an explicit limitation: contact details are not returned, so the user must be sent to the listing URL. It does not contrast against siblings like fetch or get_catalog, but the usage context is clear.

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