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

Annotations already declare readOnlyHint=true and idempotentHint=true, and the description adds meaningful context beyond that: the metric's definition, the >40% severe-stress threshold, source provenance, and coverage of 211 countries. No contradiction with annotations.

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 sentences with no wasted words: the first states the core action, the second adds the interpretation threshold, and the third covers source, coverage, and accepted code formats. Information is front-loaded and every sentence 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 and rich annotations, the description covers purpose, metric definition, threshold, provenance, country coverage, and accepted code formats. Nothing essential for selecting and invoking the tool is missing.

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 the baseline is 3. The description reiterates the accepted country code formats (alpha-2, alpha-3, numeric) that are already documented in the schema, and adds no new parameter-level semantics for start_year or end_year.

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?

Specific verb 'Retrieve' plus a clearly defined resource: 'freshwater withdrawal as a percentage of available freshwater resources for a country'. It is tied to SDG Indicator 6.4.2 and FAOSTAT, making it distinct from sibling faostat tools like food_insecurity or forest_area without any ambiguity.

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 description clearly frames the use context: country-level water stress data from FAO FAOSTAT covering 211 countries, with a threshold interpretation for severe stress. It does not explicitly name alternatives or exclusions, so it stops short of a 5, but the context is unmistakable.

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