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 that the call is paid ($0.005 USDC on Base or Solana), requires no account or API key, and crucially that failed calls are not charged. It does not describe response shape beyond the data fields or pagination behavior, which keeps it short of 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-loads the paid status, then the data description, then cost and access terms in terse sentences. Each element earns its place, though the raw pricing and URL block is somewhat dense and could be trimmed without losing routing value.

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 3-optional-param, no-output-schema, no-annotation tool, the description covers what data comes back, the payment model, and the endpoint, which is enough for an agent to call it correctly. Minor gaps around failure modes (unknown protocol) and result ordering are the only missing pieces.

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% and every parameter (sort, limit, min_tvl_usd) is documented with defaults in the schema. The description adds no further parameter meaning, so the 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 for the 'axis' protocol, aggregated across chains, with APY, TVL and 7d APY change. It is clearly distinguishable from the buy_yields_token_* and buy_yields_chain_* siblings because it is scoped to one protocol rather than a token or chain, though it never explicitly names those alternatives.

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 protocol scope ('its pools across chains') implies when to reach for this tool versus chain- or token-filtered siblings, but there is no explicit when/when-not guidance or named alternative. An agent must infer routing from the tool name and the phrase 'across chains'.

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