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

Annotations already declare readOnlyHint=true and openWorldHint=true. The description adds useful context beyond that: it consumes Weatherbit quota and requires energy API access at the Business/Enterprise tier. It does not explain errors, rate limits, or response behavior, but it meaningfully covers cost and access.

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 short sentences, front-loaded with purpose, then cost/access constraints, then a parameter default. Every sentence adds distinct value with no repetition.

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?

For a read-only forecast tool with no output schema, the description covers purpose, quota, access tier, and threshold defaults. It remains incomplete on the tp parameter semantics and forecast horizon, which matter for correct invocation.

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 60%, with lat, lon, and units documented in the schema. The description adds the important threshold default of 18 C, compensating for one undocumented parameter, but it does not explain the tp enum values 'daily' and 'hourly' beyond their names.

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 and resource: 'Read degree-day and irradiance forecasts.' This clearly distinguishes it from general weather forecast siblings and from weatherbit_energy_history, but it does not explicitly name alternatives or clarify forecast scope such as daily vs. hourly.

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?

It notes quota consumption and Business/Enterprise access requirements, which implies this is a metered, premium forecast tool. However, it gives no explicit guidance on when to use this instead of weatherbit_energy_history, weatherbit_daily_forecast, or other siblings.

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