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

Annotations already establish that the operation is read-only, idempotent, non-destructive, and closed-world. The description adds meaningful workflow context: it returns a link and price, the data is measured, and the real count is supplied before any payment, which tells the agent this is a no-commitment inquiry.

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 tightly constructed sentences front-load the trigger condition and then explain the response and payment flow. There is no filler, and each sentence contributes necessary routing or behavioral 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?

For a simple one-optional-parameter tool with no output schema, the description is complete: it explains when to use it, what it returns (link and price), and the no-payment-until-measured flow. An agent has enough to call it correctly.

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?

The single optional description parameter is fully documented in the schema, including its 300-character limit and demand-signal logging behavior. The description adds no additional parameter guidance, so the baseline of 3 applies.

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 outcome—returning a custom-list request link and its price—and defines the triggering situation: when no ready-made list fits, with concrete examples like an unusual industry, county, radius, or combined industries. This clearly distinguishes it from search_lists and the other list-detail 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?

It gives a clear condition for use: when no ready-made list fits, including several illustrative edge cases. The alternative is implied as ready-made list search rather than named explicitly, so it falls just short of fully explicit when/when-not routing.

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