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

With no annotations, the description carries the full burden, and it does clarify that this is a non-mutating 'Returns' operation with forecast and projection behavior. It does not disclose billing/auth implications, prerequisites such as block_save, or latency/error behavior, though the schema partially covers billing and prerequisites.

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 front-loaded: one sentence for purpose, one for output components, and one for interpretation. All three earn their place, though the interpretive final sentence is a slight luxury rather than essential.

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?

The tool has an output schema and mostly well-described parameters, so the description need not re-explain returns or param syntax. It is still missing explicit routing guidance and behavioral caveats, and relies on the schema for prerequisites and billing, making it adequate but not complete.

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 already covers three of four parameters with detailed descriptions, so the description does not need to repeat them; it adds conceptual context about ground variability ('bench to hollow'). It does not compensate for the undocumented dpop_token field, leaving that parameter's meaning to inference.

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 opening 'Growing degree day accumulation across a region, season to date' clearly specifies the metric and temporal scope, and the next sentence enumerates the returned components. It does not explicitly contrast with sibling tools like crop_gdd_status or soil_temp_projection, so it stops 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?

The description implies when to use it by emphasizing that the spread 'decides whether one planting date serves the whole block,' which gives decision context. However, it never states when not to use it, names alternatives, or specifies conditions that would route to another tool.

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