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

With no annotations supplied, the description carries the full burden and does well: it discloses that the call is paid ($0.002 USDC on Base or Solana), requires no account or API key, and that failed calls are not charged. It omits response shape details and any rate-limit or latency expectations, which keeps it below 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?

The description is compact and front-loaded: purpose first, then pricing/auth terms, then the endpoint. Every sentence carries information. The leading one-word 'Paid.' is terse but effectively signals the cost model up front.

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?

There is no output schema and no annotations, so the description must cover returns and safety, and it does list the key returned metrics (APY, TVL, 7d APY change) plus cost and auth requirements. The remaining gap is the exact response envelope and pagination behavior across the 1-100 row limit, which an agent may need to know.

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% — sort, limit, and min_tvl_usd each carry their own enum-ish values, ranges, and defaults in the schema. The description adds no additional meaning about these parameters (e.g., whether min_tvl_usd filters before or after limit is applied), 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?

The description states a specific resource (live DeFi yields for the openeden-tbill protocol) and enumerates the data returned: pools across chains with APY, TVL, and 7d APY change. It is clearly distinguishable from the buy_yields_chain_* and buy_yields_token_* siblings. It does not explicitly contrast itself with other buy_yields_protocol_* tools, so it stops short of a 5.

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 implied: an agent wanting protocol-level yield data for openeden-tbill should call this. There is no explicit when-to-use or when-not-to-use statement, and no mention of the chain-level or token-level yield alternatives. Payment and auth details are supplied but those are behavioral facts rather than selection guidance.

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