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

Annotations already declare readOnly/idempotent/non-destructive, so safety is covered. The description adds a genuinely non-obvious behavioral fact: it returns regulator references and never produces listings for notaries or lawyers. It stops short of describing the return shape (names vs. URLs), so not a 5.

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 short sentences, front-loaded with 'MEXICO' and the trade-to-regulator mapping. Efficient, though the closing clause about notaries/lawyers is wedged in and could be cleaner.

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 single-parameter, no-output-schema reference tool the description covers who regulates each trade and the important negative (no listings). It does not describe the form of the answer, 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% and there is only one parameter, so the schema already carries the trade description. The description restates the same five trade values, adding no format or validation detail beyond the schema; 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?

States a specific resource (regulator/where-to-check for each Mexican property trade) with an explicit country marker, so it is clearly distinguishable from the sibling check_professional_au/br/es/in/uk tools. The phrasing 'where the reader checks' is slightly indirect about what the tool actually returns, keeping it short of a 5.

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?

The sentence 'Payotte lists no Mexican professional yet and never lists notaries or lawyers' usefully signals that this is a regulator-reference tool rather than a directory lookup. However, no alternative tool is named for actually finding a professional (e.g. trouver_expert/contacter_expert), so usage is implied rather than explicit.

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