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

Annotations already declare readOnly/idempotent/non-destructive, so the safety profile is covered. The description adds genuinely new scope context — that this returns regulator/register information rather than professional listings, and that lawyers are never listed — which prevents a wrong expectation about the output.

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 sentences, front-loaded with the country scope, and the trade→regulator mapping is packed densely with no filler. The elliptical 'where the reader checks' phrasing costs a little clarity 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?

With no output schema, the description must carry the return contract; it conveys that the answer is regulator/register guidance per trade, which is adequate for a one-parameter lookup. It stops short of saying whether concrete body names or URLs are returned, a minor gap.

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% for the single required 'trade' parameter, so the baseline would be 3. The description goes beyond the schema by mapping each trade value to its specific regulator (regional registers, Banco de España, colegios, bar associations), which clarifies what each accepted value actually retrieves.

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 states a specific resource (the regulator/register to check for each Spanish property trade) and enumerates the trades it covers, so an agent knows exactly what it returns. It signals 'SPAIN' but never names the sibling check_professional_au/br/in/mx/uk tools it is parallel to, leaving the country differentiation implicit in the name alone.

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: use it to find which body regulates a given Spanish trade. The caveat 'Payotte lists no Spanish professional yet and never lists lawyers' is a useful when-not-to-expect-listing signal, but it never names an alternative (e.g. trouver_expert, contacter_expert) or states when to prefer those over this tool.

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