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

No annotations are provided, and the description fails to disclose behavioral traits. It mentions 'PAID' and 'toll to pay' but does not explain side effects, authentication needs, or rate limits. The return value is implied but not clarified, and there is no output schema.

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 short but not concise. The second sentence introduces unrelated payment information that confuses the tool's core purpose. A well-structured description would first state the function clearly without extraneous details.

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?

Given the absence of annotations, output schema, and parameter descriptions, the description is completely inadequate. An agent cannot determine how to invoke the tool or interpret results. The description does not compensate for the missing structured information.

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 input schema has 0% description coverage for the sole parameter 'expr'. The description does not explain what 'expr' represents (e.g., mathematical expression format, allowed operations). The agent receives no guidance on how to construct valid input.

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 starts with 'Arithmetic' but then adds confusing information about being 'PAID (1 iron-cent)' and 'returns the toll to pay via x402'. This makes it unclear whether the tool performs arithmetic operations or returns a payment amount. The purpose is vague and potentially misleading.

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?

No guidance is provided on when to use this tool versus alternatives. Sibling tools like 'catalog' or 'quote' are unrelated, but no comparative context is given. The description does not mention prerequisites or scenarios where this tool is appropriate.

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