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

Annotations already declare readOnlyHint=true, destructiveHint=false, and openWorldHint=false. The description adds useful context beyond them: the returned fields, the data snapshot date, and a cost-comparison/legal-advice disclaimer.

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-loads the main use case, then the exclusion, then freshness and disclaimer context. Each sentence carries useful information with no repetition.

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?

Given one optional parameter, a present output schema, and clear read-only annotations, the description supplies everything needed: use case, exclusions, return contents, snapshot date, and scope disclaimer.

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?

The single optional region parameter is fully documented in the schema, so the schema does the heavy lifting. The description reinforces regional filtering and gives examples, but adds little syntax or behavior beyond the schema description.

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?

Names a specific verb and resource (list countries), states the EOR Scope coverage scope and regional filtering, and distinguishes the tool from employer_cost. An agent can identify it without opening the schema.

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?

Explicitly says when to use it (user asks which countries are covered or wants countries in a region) and when not to use it (detailed country cost, use employer_cost). This is strong routing guidance against a relevant sibling.

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