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

With no annotations, the description must carry the full burden and it excels: it reveals scale (~1,000 instruments, one full-chain read), disloses the skew caveat (moneyness proxy, not delta-space), defines missing-data behavior (expiries with < 6 strikes are typed missing, never noise), flags coverage limits, and specifies authentication (Auth: X-API-Key). It even interprets the iv_rv_ratio field. Nothing is hidden.

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?

Purpose is front-loaded and every sentence carries information — scope, contents, caveats, coverage, data-vs-score nature, auth. It is dense but not bloated, and the length is justified because there is no output schema for the description to defer to.

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?

For a tool with no output schema and no annotations, the description is remarkably complete: it lists the returned fields, explains the missing-expiry semantics, describes coverage, and states auth. Minor gaps are the lack of an explicit output format/units statement and no explicit param-by-name documentation.

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 0%, so the description must compensate. It does partially by signalling that BTC/ETH have deep chains while other currencies are thin, which informs the symbol parameter. But it never explicitly ties the text to symbol or asset_class by name, and asset_class is documented only by the schema's enum and default.

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 states a specific verb (call) and resource (the implied-volatility surface for BTC or ETH options) and enumerates its contents (ATM term structure, skew, open-interest ratio, max pain, IV index, realised vol). It clearly distinguishes itself from derivative siblings like basis/funding/open_interest by positioning itself as 'the OPTIONS market's view'.

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?

'Call this for the OPTIONS market's view' is an explicit when-to-use trigger, and 'DATA context, not a score' provides a when-not-to-use exclusion. Coverage guidance ('Deep chains exist for BTC and ETH only; other currencies report thin') further directs symbol choice. However, no alternative tool is named explicitly, so it stops short of the top score.

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