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

Annotations already declare read-only, idempotent, closed-world and non-destructive, so the safety profile is covered. The description adds behavioral context beyond that by disclosing data-freshness semantics (data_updated, latest_boe_publication, update_frequency) and confirming the call takes no arguments, though it says nothing about result size or whether counts can be stale.

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 with no filler; the facet inventory leads and the usage guidance follows. Slightly better front-loading would put the purpose before the field enumeration, and the parenthetical freshness list is dense but earns its place.

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 an output schema present, the description does not need to explain return shapes, and annotations carry the safety profile. For a no-argument, read-only discovery tool, everything an agent needs to decide to call it is present.

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?

There are zero parameters and the description explicitly confirms 'No arguments,' matching the empty schema with additionalProperties false. No further parameter meaning is needed.

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 specific resource (facet counts of current listings by type, procedure, asset type, province) and the extra data returned (price range, countries, freshness fields). It is instantly distinguishable from get_listing (single record) and search_listings (the consumer of these filter values).

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 explicitly states two use cases: discovering valid filter values for search_listings, and answering 'how many / how fresh' questions, which routes the agent away from the search siblings. It never states a when-not-to-use condition, but the positive routing is clear enough to act on.

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