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 bar is lower. The description still adds real value: it discloses dataset scope (63 providers) and, importantly, that a fee ceiling or coverage minimum excludes/only matches providers that publish that figure, which no annotation conveys.

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 tight sentences, front-loaded with what the tool returns, followed by the one behavioral caveat that matters. No filler; every clause earns its place.

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 enumerating the returned fields (monthly fee or quote-only, countries, owned-entity footprint, delivery model, source links), and it documents the non-obvious filter behavior. Complete enough for an agent to call it correctly.

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 the baseline is 3. The description goes beyond the schema by clarifying the exclusion behavior of max_monthly_fee_usd and min_countries (only providers publishing that figure match), adding filter semantics the schema states only per-parameter.

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?

States a specific verb ('List and filter') and resource ('the 63 employer of record (EOR) providers BestEOR.co tracks'), and even enumerates the returned fields. It is clearly distinct from compare/get/estimate siblings by implication, but never explicitly names or differentiates against them, which is the 4-vs-5 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?

Usage is only implied through the filter parameters; there is no explicit when-to-use, when-not-to-use, or routing to a specific alternative sibling. The one caveat about fee/coverage filters is semantic, not usage guidance.

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