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

Annotations already cover the safety profile (readOnly, idempotent, non-destructive, not open-world), so the bar is lower; the description still adds real substance: the data source, the default TVL floor and sort order, and the exclusion of tokenized treasuries. It does not discuss freshness/latency or result caps beyond the default.

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?

Dense but front-loaded: the resource and scope come first, then row contents, then defaults, then the disclaimer. Clause-heavy sentences carry real information without padding, though the parenthetical structure is slightly hard to parse on first read.

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 no output schema, the description compensates by enumerating what each row carries (category group, base vs reward APY, 30-day mean APY, TVL) plus defaults and exclusions. An agent has everything needed to call and interpret this read-only list tool.

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 the baseline is 3, but the description adds meaning beyond the schema by explaining that 'group' corresponds to the protocol category groups (lending, vault, credit, basis) and by restating the default $10M TVL floor and highest-APY-first ordering with rationale. That is more than the raw field descriptions provide.

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: current stablecoin yield venues across named stablecoins, limited to single-asset pools on lending markets and vaults. It explicitly distinguishes itself from the tokenized-treasury tools, which is exactly the sibling overlap an agent needs resolved.

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?

Gives clear context (spot yields, DefiLlama sourced) and an exclusion ('excludes tokenized treasuries, which have their own tools'), implicitly routing the agent to those sibling tools. It never names the alternative tool explicitly the way a 5 would, but the routing signal is unambiguous.

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