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

Annotations already declare readOnlyHint, destructiveHint, idempotentHint. The description adds a useful extra disclosure: 'Read-only, no personal data', which goes beyond the annotations. It also explains the behavioral nuance of returning 'the one change most associated with fastest improvement,' providing context beyond what annotations convey.

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 two short paragraphs, front-loaded with the core action. Every sentence adds value, with no repetition of schema or annotation content. It is 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 simple one-parameter, read-only tool with rich annotations and an output schema, the description is complete. It provides sufficient context about the Cracks Index and the tool's purpose without needing to detail return values or error handling.

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 already covers the single parameter iso3 with a clear description and example. The tool description adds no extra parameter-level detail, but given 100% schema coverage, the baseline of 3 is appropriate.

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 'Return the single highest-impact improvement for one country', which is a specific verb+resource+scope. This clearly distinguishes it from sibling tools like country_detail (general info) and improvement_guidance (broader guidance) by focusing on a single, tailored fix.

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 implies when to use this tool: when you want the single most actionable improvement for a country, 'turning a ranking into a constructive, actionable signal.' It provides clear context but does not explicitly mention alternatives or exclusions, so it stops short of a full 5.

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