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

Annotations already declare readOnlyHint=true and destructiveHint=false, so safety is covered. The description adds genuinely non-obvious context: it discloses a cost model ('Paid in USDC on Base') and a return-value caveat (check matched_strike against your requested strike, since a large gap means no rung exists). No contradictions.

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 identity and use condition; every sentence carries information. The middle sentence is dense and packs two distinct ideas (rung matching plus a diagnostic check), slightly reducing scannability, but nothing is wasted.

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, return-field enumeration is unnecessary; the description still covers the one interpretive subtlety (matched_strike vs requested strike). Cost model, alternative routing, and behavioral scope are all present, leaving no gap an agent needs to call it correctly.

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 schema already documents both parameters, giving a baseline of 3. The description reinforces the strike-to-rung lookup behavior but adds no syntax or format detail beyond the schema's own descriptions.

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 relationship ('thin wrapper around prediction.hip4_price_ladder') and defines the returned unit precisely ('the single rung closest to the requested strike'). It clearly distinguishes itself from its sibling by scope: one strike vs the full ladder.

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?

Explicitly says when to use it ('when you only need one strike's Yes probability, not the full ladder') and names the alternative (hip4_price_ladder) for when a rung is missing. Both the selection condition and the fallback are stated.

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