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

Annotations already indicate a read-only, idempotent, non-destructive operation. The description adds useful behavioral detail beyond that: the 50-delta strike selection rule, the default call option behavior, and support for puts. It does not deeply describe output formatting or data range, but the annotations lower the burden for safety-related behavior.

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 efficiently structured: the core function is front-loaded in the first sentence, behavioral details follow, and use cases are listed last. Every sentence adds information without redundancy or padding.

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 read-only data retrieval tool with no output schema, the description covers the key inputs, the selection methodology, the default call/put behavior, and typical use cases. It could quantify historical depth or output format, but an agent has enough to decide when to invoke it and what to expect at a high level.

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 baseline is 3. The description adds some nuance—notably that call ATM IV is the default and puts are supported—but most parameter meaning is already supplied by the schema, including the expiration consistency guidance.

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 ('Get') and a specific resource: the historical at-the-money implied volatility time series for a ticker. It further distinguishes itself by explaining that it returns the strike closest to 50-delta and its IV, which separates it from general options history or vol history tools.

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 usage context by listing concrete applications: VRP calculations, term structure, regime detection, and vol/directional forecasting. It does not explicitly name alternative sibling tools or exclusion criteria, but the use cases are specific enough to guide an agent.

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