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

With no annotations the description carries the full burden, and it delivers more than the minimum: names the data source (DefiLlama), discloses a non-obvious filtering behavior (sane-APY cap that drops runaway incentive numbers), and states per-call cost ($0.02 USDC on eip155:8453). It omits rate limits, freshness/latency of the live data, and whether results are cached.

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 sentences, front-loaded with the core action and resource, then returns, then usage. The returns clause and usage clause overlap somewhat on filtering terms, costing a little tightness, but nothing is filler.

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?

No output schema exists, but the description enumerates the return fields (project, pair, chain, APY, TVL), so an agent knows the shape of the result. Combined with the disclosed source and cost, a caller has enough to invoke it correctly, though freshness and pagination behavior for the 'top N' list are unstated.

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% and all four params are self-described, so the schema does the heavy lifting. The description echoes the same filters (chain, stablecoin-only, min TVL, top-N) without adding units, format, or default semantics beyond what the schema already provides.

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 verb (returns/discovery) and resource (lending/liquidity pool yields from DefiLlama) and names the sibling relationship explicitly — 'the discovery step before reward-rate math' distinguishes it from crypto_apr_apy. An agent can tell it apart from crypto_new_pools and crypto_stablecoin_metrics without opening any schema.

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?

Gives a clear when-to-use ('Use this when an agent needs to top APY pools filtered by chain, TVL and stability') and routes to the reward-rate math step as the downstream alternative. No explicit when-not guidance or prerequisites beyond the implied read context.

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