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

With no annotations supplied, the description carries the full burden and does a solid job of it: it discloses that calls are paid ($0.01 USDC on Base or Solana), that no account or API key is needed, and that failed calls are not charged — the key facts an agent needs before invoking a paid endpoint. It omits rate limits, payment mechanics, and the response shape, which keeps it out of the top band.

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?

Four compact sentences with zero filler: purpose, data source, price/payment, and access constraints, followed by the endpoint. Every clause carries information an agent would otherwise have to guess.

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 three-optional-parameter read tool with no output schema, the description covers purpose, data provenance, cost, and access requirements, and it enumerates the returned metrics. The only real gap is that it does not characterize the response structure (e.g. per-pool rows, units) beyond naming the fields.

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 description coverage is 100% (sort, limit, min_tvl_usd each documented with defaults), so the schema already explains all three parameters. The description adds no extra meaning about defaults, sorting semantics, or what min_tvl_usd filtering means relative to the reported TVL, so baseline 3 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?

The description names a specific resource (live DeFi yields for the sanctum-infinity protocol), the scope ('its pools across chains'), and the returned fields (APY, TVL, 7d APY change). This lets an agent separate it from the chain-scoped buy_yields_chain_* and token-scoped buy_yields_token_* siblings without opening the schema, though the distinguishing relationship is implied by the scope wording rather than stated outright.

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?

Usage is implied by the protocol scope — call this when you want yields for sanctum-infinity pools specifically — but there is no explicit when-to-use/when-not-to-use guidance, no mention of the sibling alternatives, and no note on whether other protocols require separate calls.

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