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

Annotations already declare readOnly, idempotent, openWorld, and non-destructive. The description adds useful behavioral context beyond annotations: it names the data source timeframe, lists computed metrics, mentions 'premium synthesis over the options-history store,' and includes a disclaiming note that it is an analytical aid, not investment advice.

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?

The description is a single focused paragraph that front-loads the main action and then enumerates the derived metrics. Each clause adds useful information, though 'Premium synthesis over the options-history store' is slightly jargon-heavy and could be clearer.

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 3-parameter tool with no output schema, the description provides strong context: data source, metric definitions, lookback interpretation, and a disclaimer. It does not explicitly describe the response format, but the enumerated metrics give an agent a clear picture of what the tool returns.

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 description coverage is 100%, so the schema already documents ticker, as_of, and lookback_days with defaults and examples. The description reinforces the meaning of the lookback window through 'IV Rank' and 'IV Percentile' definitions, but it does not substantially add parameter-level detail beyond the schema.

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 action ('Compute'), a precise resource ('derived options-volatility analytics for a US ticker'), and lists the exact metrics produced. It clearly distinguishes this from raw-data siblings like options_history_volhist by emphasizing 'derived' analytics.

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?

The description gives clear context: this tool synthesizes/derives volatility analytics from historical series, so an agent can infer when to use it instead of raw-history or quote tools. It does not explicitly name alternatives or provide exclusion criteria, but the intended role is clear.

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