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

Annotations already establish that this is a safe, read-only, idempotent, non-destructive, closed-world operation. The description adds meaningful behavioral context: the returned metrics, inclusion of the window, return count and risk-free rate, and the precise rule for alpha_test.significant. It does not cover failure modes or ticker-validation 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 front-loaded with the core purpose and then enumerates the returned metrics, which is justified because there is no output schema. It is dense and somewhat long, but every sentence—including the alpha significance rule—adds useful information rather than repeating structured fields.

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?

With no output schema, the metric enumeration is essential and the description provides it comprehensively, along with both operating modes and the alpha significance condition. It stops short of explaining benchmark selection or error cases, but is otherwise sufficient for correct invocation.

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%, so both ticker and versus are already documented. The description clarifies that versus produces a two-ETF comparison page view, which adds slight value beyond the schema, but it gives no additional format or constraint details.

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 resource and scope: a risk/return scorecard for one ETF against its ETFIQ benchmark, or a pair scorecard when versus is supplied. It distinguishes the single and pair modes clearly, but does not explicitly differentiate itself from siblings such as compare_to_benchmark or etf_compare.

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?

Usage is implied by the mode description: use ticker alone for one fund against its own benchmark, or add versus for a side-by-side pair. There is no explicit guidance on when this tool is preferable to sibling comparison tools, and no exclusions or prerequisites are stated.

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