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

Read-only/idempotent semantics are already in the annotations, so the description doesn't need to repeat them. It adds real context beyond them: sorting order (lowest first), how AnswerAmerica's prepaid credits are priced as a minimum upfront package, that quote-only vendors are grouped separately, and vendor-specific caveats (message-only, law firms only). The data source and freshness date are also disclosed.

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?

Purpose and sort order are front-loaded, followed by vendor caveats and finally provenance. It is one dense block with no wasted sentences, though the run-on structure and last-sentence URL make it slightly harder to scan than a broken-out list would be.

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 still communicates the ordering and grouping of results and the special-case vendor handling, which is what an agent needs to interpret output. It stops short of describing the returned fields or units, but the essentials for correct invocation and interpretation are present.

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 all four parameters are already documented, including defaults for category and minutes_per_call. The description restates those defaults and clarifies that cost is computed jointly from volume and call length, but adds no parameter semantics the schema lacks (e.g., vendor id format, valid vendor names).

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 tool performs a specific action (price comparison) on a specific resource (answering services) with a clear scope: cost at a given call volume and call length, sorted lowest first. It is distinguishable in practice from 'category_range', 'get_vendor_pricing' and 'list_vendors', but never explicitly contrasts itself with them.

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?

Usage is implied rather than stated: 'at a call volume and call length' plus the default assumptions (live services, 3-minute calls) tell an agent roughly when this applies. There is no explicit 'use this when... / use X instead when...' guidance relative to the sibling tools.

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