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

Annotations already mark the tool as read-only and idempotent, so the bar is lower. The description adds significant behavioral detail: it names the returned components, explicit change types, CAGR validity condition, exact units, evidence hash, and a meaningful as-of-year guarantee that future releases never leak into historical results.

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, each earning its place: the first states the action, the second lists outputs, the third gives usage examples, and the fourth warns about as-of semantics. No filler or redundant restatement of schema fields.

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?

There is no output schema, so the description carries the burden of explaining return values, and it does: component observations, changes, CAGR, units, evidence hash, and caveats. Combined with full schema coverage for parameters, the definition gives an agent enough to select and invoke the tool correctly.

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 adds extra semantics beyond the schema, particularly the as-of-year behavior ('never mixes future releases into a historical result'), which is not captured in the parameter description alone.

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 uses a specific verb-resource pairing: 'Calculate prior-year and exact five-year changes for one final annual USDA NASS national crop series.' The 'one final annual national crop series' scope clearly separates it from siblings like usda_nass_crop_history, usda_nass_compare_crop_years, and usda_nass_search_crop_series.

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 gives concrete, grounded examples ('how has corn yield changed?', 'five-year soybean production trend') that make intended usage obvious. It does not explicitly say when not to use this tool or name alternative tools, so it stops short of a 5.

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