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

Beyond the annotations (readOnly/openWorld/idempotent/non-destructive), the description discloses three non-obvious behavioral traits: geometry is intentionally excluded because files can exceed 10MB, no auth is required, and the data source is William & Mary geoLab. These details add real value an agent needs before invoking the tool.

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?

Approximately 70 words with the purpose front-loaded, a compact enumeration of return fields, a critical caveat about geometry, and source attribution. Every sentence earns its place; there is no filler or repetition of schema content.

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 a rich schema, output schema, and strong annotations, the description covers the core call semantics, the large-file caveat, auth requirements, and provenance. The only gap is that it does not explicitly route the agent to the sibling level-availability tool for checking country-dependent ADM3-ADM5 support, but nothing essential is missing for a correct invocation.

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 100%, so the baseline of 3 applies; the schema already documents the ISO alpha-3 format requirement, the ADM enum, and the ADM0 default. The description adds the hierarchy semantics (country outline vs state/province vs county/district) but does not materially go beyond what the schema already provides.

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 a specific verb and resource ('Get metadata for one country's administrative boundary at a given level') and enumerates the exact payload: official name, admin unit count, area/perimeter stats, source, license, and download URLs. It is clearly distinct from the sibling tools, which focus on listing available levels and countries rather than retrieving detail.

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?

Provides clear context: this tool returns metadata and download URLs, and explicitly warns that geometry is NOT embedded in the response and should be fetched from the returned URL. It also explains ADM level semantics and notes that ADM3-ADM5 are country-dependent, implying availability should be checked elsewhere, but it does not explicitly name geoboundaries.boundary.available_levels as the alternative.

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