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

With no annotations, the description carries the full burden, and it does disclose the commercially important behaviour: $0.01 USDC on Base or Solana, no account/API key, and failed calls not charged. It does not state that it is a read-only lookup, how many rows or what shape comes back, or whether results are cached/stale, which leaves real gaps for an unannotated tool.

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 'Paid' before anything else, then packs scope, fields, price, and auth into two dense statements with no filler. The endpoint URL is arguably redundant but is a single trailing token, not a structural problem.

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 tool, the description usefully enumerates the returned metrics in place of an output schema and warns about cost. However it says nothing about the parameters or result shape, so an agent still has to infer how its call will behave.

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 fully documented in the schema. The description adds no defaults, units, or interaction guidance (e.g. how min_tvl_usd interacts with limit) beyond what is structured, 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 tr-energy' with the returned fields (APY, TVL, 7d APY change) and the data source (DefiLlama). The protocol-level scope implicitly separates it from the buy_yields_chain_* and buy_yields_token_* siblings, though it never says so explicitly.

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?

No when-to-use guidance at all: it never says to pick this over buy_yields_chain_base or buy_yields_protocol_aave-v3, nor what conditions make protocol-level yield lookup the right call. The only context given is payment mechanics, not selection criteria.

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