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

Annotations only declare readOnlyHint=true, so the description carries the rest of the burden and does: it names the data source (Deribit), the exact metrics returned including USD vs native denomination, and the liquidity profile per underlying. That liquidity-depth warning is exactly the kind of behavioral context annotations cannot express.

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?

Three dense sentences, each with a distinct job: what is returned, which expiries exist, which underlyings and how liquid. No filler and the resource definition is front-loaded.

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 no output schema, the description compensates by enumerating the returned fields and their denominations, and it flags underlying coverage limits. For a read-only, seven-parameter chain fetch, an agent has everything needed to call it correctly and interpret the result.

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 all seven parameters including the enum and the 'next'/date/exchange-code expiry formats. The description's defaults (next expiry, ±10% spot, both types) largely restate what the schema already declares, adding little beyond it.

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 and resource: a Deribit crypto options chain for one underlying and expiry, calls/puts by strike. The enumerated return fields (bid/ask/mark, mark IV, Black-76 delta, OI, 24h volume) make it unmistakably the raw-chain tool rather than the sibling analytics tools (options_gamma, options_volatility, options_positioning).

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?

Gives clear operational context: which underlyings exist, that BTC/ETH books are deep while SOL/XRP/HYPE/AVAX/TRX are thin, and what the defaults are when the caller omits filters. It never names a sibling or an explicit when-not condition, so it stops short of a 5.

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