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

With no annotations, the description carries the full burden and does well: it discloses the paid model ($0.002 USDC on Base or Solana), that no account or API key is required, that failed calls are not charged, and that data comes from DefiLlama. It stops short of rate limits or per-call quota behavior, which is the remaining gap.

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?

Dense and front-loaded: dataset scope, output fields, data source, and pricing come before the trailing URL. Slightly telegraphic phrasing but nearly every clause carries a fact an agent needs before paying for a call.

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-required-param paid read tool with no output schema, the description covers cost, payment rails, auth expectations, billing on failure, and the returned metrics. Only ranking/tie-breaking behavior and result freshness are unaddressed.

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 sort, limit, and min_tvl_usd are already documented with defaults. The description's 'top pools by TVL or APY' loosely echoes the sort option but adds no detail on min_tvl_usd filtering or the string-typed numeric inputs, 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?

States a specific verb and resource ('Live DeFi yields on Arbitrum: top pools by TVL or APY') and enumerates the returned fields (base/reward APY, TVL, 7d APY change). The chain-specific naming makes it distinguishable from the many buy_yields_chain_* and buy_yields_protocol_* siblings without opening a 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?

The 'Paid' prefix and price establish that this is a paid lookup, which implicitly tells the agent when to invoke it, but there is no explicit when-to-use/when-not guidance and no mention of alternatives such as buy_tvl_arbitrum or buy_yields_protocol_* tools for a single protocol. Usage is implied by the chain scope rather than stated.

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