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

Annotations already declare readOnly, idempotent, non-destructive and open-world, so the safety profile is covered. The description adds genuine value beyond that: it enumerates the returned components (observations, absolute/percent changes, CAGR, units, evidence hash, caveats) and discloses the as-of-year behavior of never mixing future releases into a historical result.

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?

Four sentences, front-loaded with the core purpose, followed by return contents, example queries, and a caveat. Every sentence carries information with no obvious padding, though the example list is slightly verbose.

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 appropriately describes what is returned and the semantics of the as-of parameter. It is complete enough for an agent to call correctly, though it omits explicit sibling routing that would make it fully self-sufficient.

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 the baseline is 3. The description goes beyond the schema by explaining the semantic effect of the optional as-of year ('never mixes future releases into a historical result'), adding meaning that the schema field text does not convey.

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 (calculate) and resource (prior-year and exact five-year changes for one final annual USDA NASS national crop series), which is clear and distinctive. It does not explicitly differentiate itself from siblings like usda_nass_crop_history or usda_nass_compare_crop_years, so it falls 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?

Provides concrete example queries ('how has corn yield changed?', 'five-year soybean production trend'), which implies when to use it. However, it never states when NOT to use it or names the alternatives (crop_history, compare_crop_years, evidence_pack), leaving routing to inference.

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