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

Annotations already cover read-only/idempotent/open-world safety, so the bar is lower, but the description adds meaningful behavior: silent failure on guessed codes, and the practical consequence of calling this first. It does not describe pagination or the exact shape of each returned code entry.

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?

Front-loads the purpose, then the ordering rule, then a concrete example. Dense and mostly waste-free, though the example sentence is long and could be tightened.

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?

No output schema exists, and the description conveys what comes back (valid codes per dimension) well enough to call the tool. A brief note on limit/search interaction or grouping of returned codes would make it fully complete for a 4-param lookup tool.

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%, so baseline is 3, but the description adds concrete domain-specific examples beyond the schema: dimension 'element' yields production quantity (5510), area harvested (5312), yield (5412), and 'item' in QCL covers 278 crops and livestock products. That illustrates real usage semantics the schema alone does not.

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 verb+resource: it returns the valid codes for one dimension of one FAOSTAT domain, with a concrete enumeration of the dimensions (country/area, element, item, year). It is clearly distinct from faostat_domains (which supplies the domain) and faostat_data (which consumes these codes).

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?

Explicitly instructs 'Call this BEFORE faostat_data' and gives the reason (codes are numeric and domain-specific, so guessing yields empty results rather than an error). This is a genuine when-to-use rule with the alternative named.

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