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

Goes well beyond the readOnly/openWorld annotations with genuinely load-bearing behavior: 'Data only', an explicit price point, the x402/USDC-on-Base payment channel and the exact _meta["x402/payment"] key, and a clear failure-mode policy ('bad input is free; nothing is charged when no venue answers'). For a paid tool with no output schema this is exactly the disclosure an agent needs before calling.

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 purpose and data fields, then operational concerns (pricing, payment, free-on-failure) — no filler sentences. The first sentence is a dense semicolon-chained run-on that is harder to scan than it needs to be, which costs it the top score.

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 2-parameter read tool with no output schema, the description covers everything an agent needs: what is returned, what the optional parameter changes, cost and payment mechanics, and failure-mode billing. Nothing material is left to guesswork.

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 fully documents both fields; the description adds meaning by stating what 'expiry' unlocks (that expiry plus its chain with each venue's greeks). Minor deduction: it scopes the tool to 'BTC and ETH options' while the schema advertises SOL, PEPE and aliases, leaving the agent slightly unsure of the supported universe.

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?

Names a specific resource (crypto options IV per expiry) and enumerates the exact measures returned: ATM IV, 25-delta skew, put/call OI ratio, max pain, DVOL, plus per-strike chains with greeks. The options/expiry framing cleanly separates it from the perp- and futures-oriented siblings (perp_funding_rates, futures_basis, open_interest) without needing to name them.

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?

Usage is only implied: 'Volatility surface inputs for BTC and ETH options' suggests a modeling use case, and 'with an expiry, the options chain per strike' tells the agent what the optional parameter unlocks. There is no explicit when-to-use-this-vs-a-sibling guidance and no statement of exclusions (e.g. that perp IV/term structure lives elsewhere).

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