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

Annotations cover read-only/open-world/idempotency, and the description adds genuinely useful non-annotation context: cost ($0.01 in USDC per call via x402 or prepaid credits, plus a free trial) and the risk model behind the ranking. It stops short of stating rate limits or result freshness, so not 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?

Two dense sentences plus a short example: output fields and risk methodology come first, then example, then filters and price. No filler, and the most decision-relevant information (ranking basis, cost) is front-loaded.

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?

With an output schema present, the description does not need to enumerate return fields, though it does so anyway. It covers cost, ranking logic, filters, and an example — sufficient for a zero-required-parameter query tool, with only minor redundancy against the output schema.

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 all 8 parameters are already documented with enums and defaults. The description only restates the filter list and gives one example tuple, adding little syntax or semantics beyond the schema — 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+scope: 'Best DeFi yields for a token and chain, ranked by risk-adjusted APY (sustainable APY, discounted for risk)'. This clearly distinguishes it from siblings like defi-protocol (protocol metadata) and defi-exploits (hack history) by describing a ranked pool-yield lookup.

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?

It provides a concrete example invocation ('token: USDC, chain: base, minTvlUsd: 1000000') and lists available filters, which implies usage. However, it never says when to prefer this over adjacent tools (defi-protocol, token-report, stablecoin-depeg) or state prerequisites/exclusions, so routing guidance is only implied.

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