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

Annotations already declare readOnlyHint, idempotentHint, and non-destructive, so the safety profile is covered. The description usefully adds that the estimate is model-based ('using typical take rates') rather than measured data, and points to a fuller version, but says nothing about output format or precision.

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 sentences, front-loaded with the actual purpose, with no wasted preamble. The trailing promotional URL is slightly extraneous but does not obscure the core statement.

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 description should carry more of the burden of explaining what comes back. 'Estimate the extra revenue' hints at the result, but the shape of the output (a single figure vs. a breakdown) is not described, leaving a gap for a calculation tool.

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 every parameter (including the enum and the override) is already documented in the schema. The description only echoes the 'typical take rates' behavior behind takeRatePctOverride, adding no syntax or format detail beyond the schema; 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 states a specific verb and resource: 'Estimate the extra revenue from adding a secondary action... on a thank-you page,' and names the four action types. This is far more specific than a tautology, though it does not explicitly distinguish itself from the many other revenue/pricing calculators among its siblings.

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 scenario ('adding a secondary action on a thank-you page'), so an agent can infer context. However, there is no explicit when-to-use, when-not-to-use, or reference to an alternative tool among the numerous sibling calculators.

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