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

Annotations already declare read-only, idempotent, non-destructive, closed-world behavior, so the bar is lower. The description adds real value beyond that: the total dataset size (93), the returned fields, and the non-obvious filter semantics that quote-only providers silently drop out of fee/coverage constraints.

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 sentences, no filler: the first establishes scope and payload, the second carries the one subtle filtering rule. Front-loaded with the resource and count, and the caveat is placed after the payload rather than buried.

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 correctly compensates by naming the return fields (fee, countries covered, entity footprint, delivery model, source links). Combined with the annotation safety profile and full schema coverage, an agent has enough to call this correctly; only an explicit sibling-routing statement 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% — every parameter, including both enums, is documented in the schema itself. The description's filter caveat largely restates the max_monthly_fee_usd schema note about excluding quote-only providers, so it adds little semantic detail the agent couldn't already read.

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 opens with a specific verb+resource ('List and filter the 93 employer of record (EOR) providers') and enumerates what each record contains, so the agent knows exactly what comes back. It doesn't name a sibling, but the 'list and filter' framing implicitly separates it from match_eor_providers and compare_eor_providers.

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 by 'list and filter' — there is no explicit statement of when to choose this over match_eor_providers or compare_eor_providers, which are the obvious alternatives for similar intents. The one genuine guideline is the caveat that a fee ceiling or coverage minimum only matches providers publishing that figure.

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