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

Annotations already cover the safety profile (readOnly, idempotent, non-destructive, closed-world), so the description clears the lower bar by adding real context: no charge or account needed, and authenticated calls additionally return workspace balance. The explicit non-side-effect list (no send, no checkout, no funding) is the kind of detail annotations cannot convey.

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?

Three short sentences, front-loaded with the core action and followed by the auth/side-effect constraints. Slight redundancy between "no account or charge required" and "fund an account", but nothing wasteful.

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?

The output schema exists, so return values need not be described, and the auth/no-charge semantics are well covered. What is missing is a routing rule against the crowded quote siblings and any guidance on the three undocumented boolean parameters, which for a zero-required-parameter tool leaves notable ambiguity.

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 only 14% – just couponCode is documented – so the description must carry the load, and it names mail class, page count, recipient count, print options and coupon. That leaves color, certified and electronicReturnReceipt only vaguely covered by "print options", with no units, defaults or interaction between mailClass and certified explained.

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?

Opens with a specific verb+resource ("Calculate a public USD physical-mail quote") and enumerates the inputs that drive the price. It does not, however, distinguish itself from the many pricing siblings (get_letter_quote, get_product_quote, quote_letter, quote_product), which the agent must disambiguate alone.

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 account or charge required" and "A quote does not send mail, initiate checkout or fund an account" give useful inclusion and exclusion context. But with four sibling quote tools, no sentence tells the agent when this generic physical-mail quote is preferred over get_letter_quote or quote_product.

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