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

Even with readOnlyHint=true annotation, the description adds substantial behavioral context: it explains the scoring formula (weekly US Drought Monitor DSCI, z-scored against 23-year baseline), lists output fields, and notes daily updates. This goes beyond the annotation and helps the agent understand data provenance and freshness.

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?

The description is compact and information-dense, with the core output statement first, followed by usage guidance and update frequency. Every sentence contributes value without redundancy, and the structure is well front-loaded.

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?

Even without an output schema, the description enumerates the returned fields, which gives the agent a solid picture of the response. It lacks detailed definitions of each field and how to interpret the stress score's magnitude, but the field names and context are reasonably self-explanatory. The daily update note and usage scenarios round out the completeness.

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?

The schema description covers the only parameter (days) with 100% coverage, so the baseline is 3. The tool description does not elaborate on the days parameter at all, but since the schema already explains its optional nature and the Gold tier requirement, no additional description is necessary.

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 clearly states the tool returns a specific 0-100 agro-ecological yield stress score with detailed methodology and named output fields. It uses the verb 'Returns' and specifies the resource (yield stress index), making its purpose unambiguous and distinct from generic siblings.

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 provides explicit use cases: 'when the user asks about drought impact on corn or soybean yields, Corn Belt growing conditions, or ag drought stress' and for grain hedges or positioning. It lacks explicit when-not or alternative tool mentions, so it doesn't fully earn a 5, but the context is clear.

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