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

Annotations already establish readOnly/idempotent/non-destructive, and the description adds real behavioral detail on top: no personal data required, taxes/fees/usage/one-time charges excluded, included features listed per plan, and specific non-success responses (term_not_supported, formal_quote_required).

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?

One dense paragraph, but front-loaded with the core definition and zero purely decorative sentences. The clause about taglines and the feature-list sentence are secondary detail that slightly dilutes an otherwise tight block.

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?

With no output schema, the description compensates by explaining returned fields, caveats, exclusions, and the escalation path. An agent has everything needed to call it correctly and to interpret or reroute an unsupported request.

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 75%, and the description adds default/omission semantics that the schema does not spell out (omitting plan returns every plan) plus the meaning of the returned monthly.low_from / high_from endpoints. It says less about the addons object, which the schema already enumerates.

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 first sentence names a specific verb (estimate), the exact resource (Accent cloud phone and team messaging plans), and the pricing basis (published 36-month rates). It is unmistakably a read-only pricing tool, easily distinguished from the site_get/site_search/site_status 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 states when to use it (36-month published rates, add-ons included), when not to (month-to-month, other terms, annual-billing online-order pricing), how to widen scope (omit plan), and hands off explicitly to next_steps.formal_quote_url for binding prices.

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