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

Annotations already declare read-only, idempotent, non-destructive, and closed-world behavior, but the description adds critical pricing semantics: amounts are in US cents, there is no volume discount, no per-page charge, no colour printing, and New York sales tax is always added regardless of destination. It also reinforces safety with 'This creates nothing and mails nothing.'

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 purpose, then packs pricing rules and quoting guidance into compact sentences with no wasted text. Every sentence earns its place.

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 zero-parameter schema, rich annotations, and an output schema that covers return structure, the description is complete. It closes the key remaining gaps: pricing rules, tax behavior, and the instruction to call before quoting costs.

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 tool takes zero parameters, so per the rubric the baseline is 4. The description adds no parameter-specific details because none exist, which 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: return the published USPS letter price list. It details exactly what the list contains (products, costs, page coverage, sales tax applicability), so an agent can distinguish it from all sibling tools immediately.

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 explicitly says to call this tool before telling a user what a letter will cost, and then instructs how to quote the result (tier total plus New York sales tax). No sibling tool offers pricing, so no alternative routing is needed.

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