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

Annotations already declare readOnlyHint=true and openWorldHint=false, so safety is covered, but the description adds real value beyond that: it discloses the $0.002 USDC cost, the two payment paths (prepaid api_key/pass token vs x402 per-call), and a ~30-minute data refresh cadence. Only the failure behavior (no pools found, invalid chain) is unresolved.

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?

Front-loaded with the cost and the core result, then the example and refresh cadence — each sentence carries information. Slight redundancy with the title ('Best yields for chain/token ($0.002)') repeats the price already stated in the first sentence.

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?

There is no output schema, and the description compensates by naming the returned fields and the result count (top 10 pools with APY, TVL, risk score). Payment and freshness, the two main behavioral unknowns for a paid tool, are both covered; only edge-case behavior 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?

Schema coverage is 100%, so the baseline is 3, but the description adds meaning beyond the schema by stating that chain and token are individually optional and can be combined ('takes chain, token or both') and by showing a concrete valid combination. It does not state what happens when both are omitted or whether ranking changes with scope.

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 a specific resource and result: top 10 pools ranked by risk-adjusted APY, returning APY, TVL and a 0-100 risk score, with an example (chain=Base, token=USDC). It is clear enough to act on, but it never distinguishes itself from the clearly related siblings free_defi_top_yields, staking_yields or lookup_pool, so an agent must infer which yield tool to pick.

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?

'Takes chain, token or both' implies how to scope the query, and the example demonstrates a typical call. However there is no explicit when-to-use vs when-not guidance, and the very similar free_defi_top_yields / staking_yields / pendle_fixed siblings are never mentioned as alternatives.

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