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

With no annotations, the description carries the burden; it usefully discloses that the output is a 1σ band computed from ATM IV for only the remaining session. It does not describe the exact output shape or edge cases, but as a read-only getter it does not hide destructive or mutating 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 one tight, front-loaded phrase with no filler; every word ('1σ', 'ATM IV', 'remaining session') contributes distinct information.

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?

Because an output schema exists, the return shape does not need explanation, and the tool is simple with a single optional parameter. However, the missing usage guidance and implicit parameter linkage leave the definition only minimally complete.

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 0% and the description does not mention the symbol parameter or explicitly connect it to the underlying used for the expected-move calculation. The parameter name and default 'SPY' make it self-explanatory enough to avoid a 1, but the description adds no parameter meaning.

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 names the resource ('expected-move band') and specifies its derivation ('from ATM IV') and horizon ('remaining session'), so an agent can distinguish it from sibling market-data tools like get_skew or get_pin. It lacks a verb, but the get_em tool name and the noun phrase make the action unambiguous.

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 'remaining session' qualifier implies the intended use case, but the description gives no explicit when-to-use or when-not-to-use guidance and names no alternatives. An agent must infer context from the sibling list rather than being told.

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