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 ($0.01 USDC on Base or Solana), requires no account or API key, is not charged on failure, and that data comes from DefiLlama. It does not mention rate limits or response envelope details, but for a paid read-only data fetch the key behavioral facts an agent needs are covered.

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 a tight sentence covering scope, returned fields, price and auth. The trailing raw URL is arguably redundant given the tool name, but overall there is very little waste.

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?

No output schema exists, and the description compensates by naming the returned fields (APY, TVL, 7d APY change) and the upstream source. Payment mechanics and auth requirements are also covered. The remaining gap is the lack of differentiation from chain- and token-scoped yield siblings, which matters given the tool's crowded namespace.

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%, with sort, limit and min_tvl_usd each documented including defaults and ranges. The description adds nothing beyond that, so the baseline 3 is appropriate — the schema does the parameter work.

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 (buy/retrieve) and a precise resource: live DeFi yields for the protocol 'mainstreet', with the returned fields named (APY, TVL, 7d APY change). An agent can distinguish it from the many buy_yields_chain_* and buy_yields_token_* siblings because the scope is explicitly protocol-level ('its pools across chains'), though the description never names those siblings 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 only implied by the phrase 'yields for mainstreet'. There is no explicit statement of when to prefer this over buy_yields_chain_base or buy_yields_protocol_aave-v3, nor any exclusions. In a namespace of hundreds of near-identical yield tools, the absence of routing guidance is a real gap.

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