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

Annotations already declare readOnly, idempotent, openWorld and non-destructive, so the safety profile is covered. The description adds genuinely useful behavior beyond that: a per-call cost of 0.01 USDC on Base via x402 and the X-Provider-Key header for customer-owned credentials. It stops short of describing error conditions, rate limits, or the exact response payload.

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?

Two compact sentences: scope and exclusions first, then payment and auth mechanics. Every clause carries information an agent needs, with no repetition of the tool name or filler.

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?

For a five-parameter, read-only calculator with full schema coverage and annotations, the description supplies the missing operational context: compute limits, cost, and credential handling. The one remaining gap is that no output schema exists and the description never explicitly states what is returned (e.g. a single gross-wage amount versus a per-worker breakdown).

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% and all five parameters carry their own descriptions including defaults, so the schema does the heavy lifting. The description only paraphrases the same inputs ('hours, base rate, optional overtime and staff count') and adds no format, rounding, or currency-handling semantics beyond what the schema already states.

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 names a specific verb and resource ('Calculate gross wages') and enumerates the exact inputs (hours, base rate, overtime, staff count). It also draws a sharp boundary against payroll-compliance tools with 'no tax or statutory payroll compliance calculation', which separates it from siblings like api_hr_invoice or api_hr_leave_accrual without needing to name 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?

It states the domain of use (small-business gross wage calculation) and an explicit exclusion (no tax/statutory compliance), which tells the agent when to pick something else for compliance work. No sibling tool is named as the alternative, so the routing is implied rather than spelled out.

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