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

Annotations already cover read-only, open-world, idempotent, and non-destructive behavior. The description adds useful non-schema context: the response is a sample, no authentication or payment is needed, and it takes zero arguments. It does not clarify whether the sample is static or live, which is a minor remaining gap.

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?

A single front-loaded sentence: the [FREE] tag, the purpose, the cost avoided, and the zero-setup nature. Nothing is wasted and the most decision-relevant fact leads.

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 zero-parameter preview with no output schema, the description gives enough to call it correctly and explains why one would (see the shape before paying). The only omission is a hint at what the sample payload contains.

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?

With zero parameters, the baseline is 4. The description reinforces this by stating 'no arguments needed', which correctly matches the empty schema.

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 frames this as a free sample/preview of the weather tool, distinguishing it from the paid sibling by mentioning the 0.004 USDC cost it avoids. It does not, however, say what the weather data actually contains (current conditions, forecast, coverage) beyond the word 'weather'.

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 states the use case explicitly — inspect the response shape before paying — and clarifies that no wallet, payment, or arguments are required. It implies but never names the paid 'weather' sibling as the alternative, so a small inference is left to the agent.

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