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

Annotations already declare readOnlyHint=true and idempotentHint=true, so safety is covered. The description adds valuable behavioral context beyond annotations: it clarifies that the output is a set of candidate scopes for restricting searches, not for destination detail lookup, and that parent-region scopes are restrictive only. This informs the agent about the tool's semantic role.

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?

Three sentences, each carrying distinct value: purpose, usage linkage, and an exclusion. No redundancy, front-loaded with the core function. Perfectly concise and well-structured.

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 single-parameter tool with no output schema, the description is largely complete. It names the return fields (entityType and entityId) and explains their downstream use. However, it does not describe the exact shape of the response (e.g., array or single object), but this isn't essential given the tool's simplicity and the explicit usage guidance.

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 schema covers 100% of the parameter's meaning, including examples ('Val Thorens', '3 Vallees') and constraints. The description does not add further detail about the parameter itself but explains how the result is used. Since schema coverage is high, baseline 3 is appropriate; the description adds no additional parameter-specific semantics.

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 clearly states the tool's function: 'Resolve a user phrase into concrete search-scope candidates' and lists the types of candidates (parent regions, ski areas, etc.). It distinguishes itself from sibling tools by explicitly linking its output to search_apartments, showing a specific verb+resource 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?

Explicit when-to-use guidance is provided: 'Use the returned entityType and entityId in search_apartments when you want to restrict a later apartment search.' It also states when to skip: 'Broad searches can skip this and use keywords directly.' The caveat about parent-region scopes adds clear exclusions.

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