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

Annotations already establish it as read-only, idempotent, closed-world, and non-destructive. The description adds useful context beyond annotations: no account is needed, no property data is involved, and fractional positions are interpolated against a generic benchmark curve.

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 return value and fallback role stated first, followed by use cases. The appended Spanish translation is slightly redundant for an English description but does not obscure the main content.

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 two-optional-parameter tool with no output schema, the description supplies enough context: return range, fallback semantics, no-auth behavior, and example uses. Nothing critical for correct invocation is missing.

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 optional parameters are already fully documented. The description mentions fractional position interpolation and expected-click conversion, but does not add syntax or constraints beyond what the schema already provides.

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 generic organic CTR curve by Google position 1–20, with values as fractions 0–1. It distinguishes itself from a property-specific CTR curve by saying it is the fallback when a property lacks its own volume.

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 clear usage contexts: use it to estimate expected clicks for a position or to explain a CTR gap, and it is the fallback when no property-specific volume exists. It does not explicitly name get_ctr_curve as the alternative for property-specific curves, leaving that inference to the agent.

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