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

Annotations already declare this as a read-only, non-destructive, open-world operation. The description adds useful behavioral context beyond them, including the JSON response fields, paid-plan rate breakdowns, and a 2-credit cost.

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 reasonably short and front-loads the core calculation, but it redundantly repeats “Sales Tax Calculator” twice before providing useful information. The remaining content is efficient, though the opening could be tightened.

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 three-parameter calculation tool with an output schema and annotations, the description covers inputs, outputs, cost, and paid-plan behavior adequately. The main missing context is how it differs from the similar SalesTaxLookup sibling.

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 the schema already explains amount, zip, and state. The description restates the same input concept without adding meaningful syntax, constraints, or examples beyond what is already structured.

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: calculate US sales tax from an amount plus ZIP code or state, returning combined rate, tax amount, and order total. It is clear what the tool does, but it does not distinguish itself from the sibling SalesTaxLookup tool.

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 implies usage by saying to send an order amount with a ZIP code or state, and the schema clarifies that state is used when ZIP is not given. However, it provides no explicit when-to-use or when-not-to-use guidance relative to alternatives such as SalesTaxLookup.

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