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

Annotations already flag read-only and open-world, and the description adds substantial context beyond them: the x402 payment requirement, the exact cost per successful call ($0.002 USDC on Base, Solana or Arc), and that failed calls are free. It also discloses the methodological limitation (no per-strike delta calls), which is the kind of constraint an agent must know before selecting it.

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 and scope are front-loaded, and the pricing line is separate and easy to scan. The main clause is dense with nested parentheticals defining moneyness, which slows parsing slightly, but no sentence is filler.

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, the description need not explain return values, and it covers everything else an agent needs: scope, defaults, the exact skew definition, the delta-skew caveat, and cost/payment behavior.

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% and both parameters already document format and defaults (30OCT26-style expiry, BTC/ETH), so the schema does the heavy lifting. The description restates the defaults but adds no new parameter syntax or validation detail, so the baseline of 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?

The description names the specific resource (Deribit BTC or ETH options for a single expiry) and the exact metrics returned (ATM mark IV and an IV skew at ±10% moneyness). It even defines the skew formula, so an agent knows precisely what it gets and that no sibling tool covers Deribit options.

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?

It states the default scope (nearest unexpired expiry, BTC) and explicitly rules out a related but different use case: 'This is a moneyness skew, not a 25-delta skew' because Deribit's summary lacks delta. That is a clear when-not signal, though no alternative tool is named for delta-based skew.

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