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

Annotations already flag destructiveHint=true and readOnlyHint=false, and the description goes well beyond them: it discloses that the whole selection is replaced (not merged), that the change resets earlier approvals to pending, and that it is gated by role and review state. Those are the consequences an agent must know before invoking a destructive write.

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 action and target are front-loaded, and the sentence order moves logically from what is set, to how, to who may change it, to what happens next. It is slightly dense and repeats the countries concept twice ('selection of countries' then 'the countries a European patent is to be validated in'), but nothing is wasted.

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 two-parameter destructive mutation, the definition covers purpose, code format, replacement semantics, authorization rules, approval side effects, and the next step. With an output schema present, no return-value explanation is needed, so nothing material 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%, so the baseline is 3, but the description adds real meaning by specifying that codes are two-letter EPC state codes or 'UP' for the Unitary Patent, which constrains the domain beyond the schema's generic pattern. review_id is left to the schema, which is acceptable given its own 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?

Opens with a specific verb and resource ('Sets the user's selection of countries on a validation review') and narrows the scope to type ENTRY_PLAN_VALIDATION with the accepted code format. An agent can distinguish this from sibling tools like get_review or respond_to_review without opening any 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 routes the agent: get_review is named for inspecting recommended and currently selected countries, and respond_to_review is named as the follow-up approval step. It also states the preconditions (review must be open, caller must be an unapproved reviewer or a specialist), which is exactly the when-to-use information needed.

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