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

Annotations already cover read-only/idempotent behavior, so the description adds value by disclosing the FolioFact Pro subscription requirement and the specific daily 30-day history scope. No contradictions with annotations; the tool is read-only and the description reinforces that.

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?

One sentence, front-loaded with the core purpose and immediately followed by the critical access requirement. Every word earns its place; no redundancy or unnecessary detail.

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?

The tool has rich annotations, a simple one-parameter schema, and an output schema, so the description does not need to explain return values. It covers the essential behavioral constraint (Pro requirement) and scope. Minor gap: does not mention that the data is historical series, but output schema likely covers this.

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% with the ticker parameter well described ('Stock ticker (dots allowed)'). The tool description adds 'for one company,' clarifying single-ticker usage, but does not introduce format details beyond what the schema already provides. Baseline 3 is appropriate.

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 clearly identifies the resource (daily 30-day implied volatility history) and scope (one company), distinguishing it from siblings like stock_earnings or get_stock. It lacks an explicit verb but the noun phrase is specific and 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 description mentions 'for one company,' implying single-stock usage, and 'Requires FolioFact Pro' sets a clear prerequisite. However, it does not explicitly state when to use this tool instead of alternatives or mention any exclusions, though sibling names suggest differentiation from general stock data tools.

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