yield_scanner

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

Annotations already cover read-only/idempotent/non-destructive/open-world, and the description adds substantive context on top: cost ('free'), auth ('no API key, nothing signed or spent'), and failure behavior (error on unknown symbol or unreachable upstream). It also discloses the risk_level heuristic caveat, which is not visible in the schema.

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-loaded with the core purpose, then cleanly labeled Use when/Not for/Returns/Example sections. The embedded example response is somewhat long, but it substitutes for the missing output schema, so it earns its place.

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?

No output schema exists, so the description compensates by describing the return shape ('list of pools with protocol, apy, tvl_usd, chain, risk_level sorted by APY descending') and giving a concrete example. Failure modes and constraints are also covered, leaving nothing essential missing.

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 three parameters (token, chain, min_tvl) are already documented in the schema. The description adds no syntax or format detail beyond the schema, 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+scope ('Find best DeFi yield opportunities across protocols for a given token') and explicitly contrasts with the sibling defi_tvl, which handles TVL rather than pool APYs. An agent can distinguish it from related siblings without opening any schema.

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?

Provides explicit 'Use when' and 'Not for' clauses naming the alternative tool (defi_tvl), plus a proactive prerequisite suggesting token_security before depositing. When-to-use, when-not-to-use, and the alternative are all covered.

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