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

Annotations already declare readOnlyHint=true, idempotentHint=true, and destructiveHint=false, so the safe read-only behavior is established. The description adds minimal behavioral context—only that the data is auxiliary location data and the action is list—without disclosing return format, pagination, ordering, or any limitations.

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?

The description is short, but it spends space enumerating states and address actions that belong to sibling tools, and it includes the technical artifact '[Flattened action: list]', which adds noise without helping an agent understand the tool's purpose or invocation.

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 and 0% parameter description coverage, the description should clarify what the list response contains and whether the optional parameters affect results. It does neither. The simple read-only domain and strong annotations prevent a score of 1, but the missing return and parameter semantics leave the tool under-specified.

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 0%, so the description carries the burden for explaining parameters. It explains country and zipcode only in the context of other actions (states and address), not for the flattened list action, and the 'account' parameter is never mentioned at all.

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 identifies the domain as Guru auxiliary location data and specifies the flattened action as 'list (países)', indicating the tool lists countries. It distinguishes from sibling tools like guru_countries_states and guru_countries_address by naming those actions, though including them in the description introduces some ambiguity about the current tool's exact scope.

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?

The description offers an implied mapping between actions and parameters ('states (country, ex.: BR); address (zipcode/CEP BR)'), which hints at when related endpoints are relevant. However, it never explicitly states when to use this list tool versus the sibling guru_countries_states or guru_countries_address tools, nor does it provide usage context.

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