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

With no annotations at all, the description carries the full burden and does it well: it discloses that the call is paid ($0.005 USDC on Base or Solana), that no account or API key is needed, and that failed calls are not charged — the billing-on-failure policy is exactly the kind of detail an agent needs before committing to a paid call. What it omits is the shape of the response (fields, ordering, row limits beyond the schema), which keeps it from a 5.

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 'Paid.' and then immediately the resource definition, followed by short billing and access clauses. Every clause carries information an agent would otherwise have to guess; the trailing URL is slightly redundant with the tool binding but not wasteful.

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?

Three optional parameters, no output schema, no annotations — the description covers what data comes back (pools, protocols, chains, APY, TVL), where it comes from, and the commercial terms. An agent could invoke this correctly from the description plus schema; only response-field details are missing, and those are minor for a list-style endpoint.

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%, so sort, limit and min_tvl_usd are already documented in the input schema. The description adds only indirect context — that results carry APY and TVL, which hints at what 'sort' toggles between — but supplies no syntax, defaults, or units beyond what the schema provides. 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?

States a specific resource and scope: 'live pools holding HYPE across protocols and chains, APY and TVL (DefiLlama data).' That is precise enough to separate it from the many siblings — buy_yields_token_khype is a different token, buy_yields_chain_* is chain-scoped, buy_yields_protocol_* is protocol-scoped, and buy_coin_HYPE is a price feed rather than a yield listing.

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 resource phrasing ('where to earn yield on HYPE'), so an agent can infer the lookup intent. However, no alternative is named and no exclusion is stated — nothing says to prefer buy_yields_chain_hyperliquid-l1 or buy_yields_protocol_hyperlend-pooled when the question is chain- or protocol-specific, so the routing decision is left to inference.

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