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

Annotations already cover the safety profile (readOnly, idempotent, openWorld=false), and the description adds substantial behavior: paging capped at 50 entries, pageCount/totalCount, clamping of excessive pages, which fields search matches, case-insensitive countryCode, Global being an implicit non-selectable default, and that the catalogue is static/account-independent. This is well beyond what annotations provide.

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?

A dense single paragraph, but front-loaded with the core purpose and paging behavior before routing and inheritance rules. Nearly every sentence adds usable information; the inheritance rule is slightly verbose but relevant to correct ref selection.

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?

Complete for a read-only catalogue tool: an output schema exists so return values need not be described, yet the description still supplies pagination mechanics with the response fields. Combined with mutation routing and default-inheritance rules, an agent has everything needed to call it and use the results correctly.

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 must carry the load, and it largely does: it explains search's match fields (ref, label, shortLabel, group, country code), countryCode case-insensitivity, kind's country/city scope, and page's paging semantics/clamping. Only the exact page numbering minimum isn't restated, which the schema's exclusiveMinimum already enforces.

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?

States a specific verb+resource ('Discover selectable country/city refs') and names the exact filter dimensions (search, countryCode, kind). It also distinguishes the tool's role by naming the consumers (add_scan_region, create_prompt/update_prompt/reactivate_prompt.regions), so an agent can place it among the ~80 siblings immediately.

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: use returned refs in add_scan_region or the prompt-region fields, and notes unknown new refs are rejected. It also explains the inheritance rule (prompt regions override scan defaults; empty override inherits defaults, then Global). No explicit 'when not to use' or alternative-listing tool, but the consumption guidance is unusually concrete.

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