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 calls are paid ($0.01 USDC on Base or Solana), that no account or API key is needed, that failed calls are not charged, and that data comes from DefiLlama. What it omits is rate limiting or latency/response-size behavior, keeping 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 most decision-relevant fact ('Paid.') and then packs data scope, price, payment rails, billing behavior, and endpoint into a few tight sentences with no filler. Every sentence earns its place.

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 0-required-param paid read tool with no output schema, the description covers what is returned (APY, TVL, 7d APY change), cost and payment mechanics, and billing on failure. It is slightly thin on what a pool record looks like or whether results are paginated, which is why it is not a 5.

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 the schema already documents sort, limit, and min_tvl_usd including defaults. The description adds no meaning about these parameters (no note on valid sort values, cost scaling with limit, or why min_tvl_usd matters), 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+resource: 'Live DeFi yields for treehouse-protocol' with 'its pools across chains'. The protocol-level scoping in the tool name plus the description's emphasis on 'its pools' implicitly separates it from the buy_yields_chain_* and buy_yields_token_* siblings, so an agent can pick the protocol-level tool without ambiguity.

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 only implied by the tool name and the protocol name in the description; there is no explicit statement of when to choose this over buy_yields_chain_base or buy_yields_token_*, nor any exclusion. The payment/cost notes are operational, not selection guidance, so this lands at the minimum-viable level.

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