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

With no annotations, the description carries the full burden. It does disclose that results are 'real-time' and specific to 0DTE options on index/ETF symbols, which is meaningful behavioral context. It says nothing about data source, whether it works outside market hours, rate limits, or how an unsupported symbol is handled.

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?

Two tight sentences: the first defines the computation and scope, the second gives the practical use case. Nothing is redundant and the core purpose 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?

For a simple one-parameter read-only computation with a fully documented schema, the description covers the essentials. The notable gap is that no output schema exists, yet the description does not indicate the shape of the result (e.g., upper/lower bounds, expected move value), which would help an agent use the return correctly.

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%, and the schema already documents the single optional 'symbol' parameter with its default and examples. The description repeats the same example tickers without adding format or validation nuance, so baseline 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 uses a specific verb ('Computes') and named resources ('0DTE Expected Move and standard deviation volatility bounds') scoped to index/ETF symbols. An agent can tell exactly what output this produces. It does not, however, explicitly differentiate itself from the sibling thesis and calendar tools, leaving that inference to the agent.

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 gives a clear intended use case ('understand expected trading ranges and optimal strike placement for credit spreads and iron condors'), which points the agent in the right direction. But there is no guidance on when NOT to use it, no mention of alternatives, and no conditions such as market hours or data freshness requirements.

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