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

Annotations already cover read-only/idempotent/closed-world, and the description adds genuinely useful context beyond them: 22 services covered, weekly refresh cadence, pricing verified against the vendor's own site, and that the response includes a last-verified date. It stops short of describing pagination or response structure depth, but the freshness/coverage notes are substantive.

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?

Front-loaded with the capability, immediately followed by return contents and then trigger phrases. Slightly redundant between 'human-verified' and the later 'date the pricing was last verified', but no sentence is wasted.

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 fully carries the burden by enumerating returned fields (plans, monthly price, included minutes, setup fees, overage, free trial, verification date). For a one-parameter read-only lookup, nothing an agent needs to call it correctly is missing.

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 100% and the single 'service' parameter already carries example values, so the baseline is 3. The description reinforces accepted naming by listing the same example vendors and noting the 22-service universe, but adds no guidance on aliases or handling of unmatched 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?

Clear specific verb+resource ('Get current, human-verified pricing for a specific answering service') with concrete example vendors. It implicitly carves out a niche versus compare_answering_services by framing itself as a single-service lookup, but never names that sibling, so an agent must infer the boundary.

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?

Strong trigger phrasing is quoted verbatim ('how much does X cost', 'X pricing', 'is X worth it'), which maps directly to user intent. It does not state when not to use it (e.g. multi-service comparisons) or that compare_answering_services should be used instead for side-by-side analysis.

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