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

Annotations already provide readOnlyHint, openWorldHint, idempotentHint, and destructiveHint, but the description adds meaningful behavior beyond them: 'refreshed every 15 minutes', '$0.003 per call (10 free/day)', and detailed output semantics like base vs reward APY, 30-day mean, IL risk, exposure, and DefiLlama's prediction. This gives the agent a clear picture of cost, freshness, and return richness.

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 dense but every clause earns its place: purpose, filters, data source, refresh rate, metric semantics, and pricing. It is front-loaded with the search action and key filters. The long first sentence is slightly crammed, but there is no fluff or repetition.

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 explaining the return content—APY split, 30-day mean, IL risk, exposure, and prediction—so the agent knows what results look like. Combined with annotations covering safety and idempotency, and defaults in the schema, the tool is fully specified for correct invocation.

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 only 56%, so the description carries responsibility for clarifying parameters. It does this by grouping filters ('chain, protocol, token, stablecoin-only, min TVL') and explaining output fields that map to sort and single_exposure_only semantics. It doesn't explicitly define limit or max_apy, but those are simple and partly documented in the schema, so the compensation is adequate.

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 opens with 'Search ~19,000 DeFi yield pools across all chains'—a specific verb and resource that immediately defines the tool's scope. It goes on to list concrete filters and returned metrics (APY split, 30-day mean, IL risk), which clearly distinguishes it from sibling tools like defi_protocol or defi_rankings.

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?

The description makes the use case obvious—finding, filtering, and sorting yield pools from DefiLlama data—while noting specific capabilities like stablecoin-only filtering and IL risk. It does not explicitly name alternatives or state when not to use it, but the context is strong enough to guide selection among the large sibling list.

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