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

Annotations already declare readOnly, idempotent, openWorld and non-destructive, so the safety profile is covered. The description adds genuinely useful context beyond that: it is free, requires no wallet or payment, needs no arguments, and returns a sample rather than live data.

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 tight sentence front-loaded with the [FREE] tag and the key takeaway (sample before paying). Every phrase earns its place with no redundancy.

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-argument preview tool with no output schema, the description adequately conveys the free, sample-only nature and the cost of the real call. It could note the preview is illustrative/possibly stale, but nothing critical is missing.

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?

Zero parameters, so there is nothing for the description to disambiguate. The statement that no arguments are needed is a reasonable confirmation, and the 4 baseline for a parameterless tool applies.

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?

States it is a free sample response for the sibling tool token_price, so an agent can tell it apart from the paid token_price and the other *_preview siblings. The title carries the actual subject matter (Base token price via Chainlink + Uniswap V3) rather than the description, leaving the description slightly thin on what data it previews.

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?

Clearly frames the when: use it to see the response shape before paying 0.003 USDC for token_price. It implies token_price is the paid alternative without naming an explicit exclusion or when-not-to-use condition.

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