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

Annotations already declare readOnlyHint=true, idempotentHint=true, destructiveHint=false, and openWorldHint=false, so the safety profile is fully covered by structured data. The description adds nothing behavioral beyond that — no note on pagination behavior (which lives only in the schema) or result size. With annotations carrying the burden, 3 is appropriate.

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?

Two short, front-loaded sentences with zero filler. The purpose is stated first and the filter capability second, which is exactly the priority order for an agent scanning tools.

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 filtered list tool with full schema coverage and complete annotations, the description is nearly sufficient: it names the returned entity (site links) and the filter keys. The only gap is that no output schema exists, so result shape and pagination semantics depend entirely on the schema's parameter descriptions rather than the tool description.

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 all four parameters (page, per_page, site_id, service_area_id) are already documented in the schema. The description confirms the filter semantics for two of them but adds no syntax, format, or interaction detail (e.g., whether filters are ANDed). Baseline 3 when the schema does the heavy lifting.

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 (list) and resource (site links for service areas), which distinguishes it from the neighboring list_sites and list_service_areas tools since it targets the association between them. It does not explicitly name a sibling, but the resource phrasing is distinctive enough to identify the tool.

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?

"Filter by service_area_id or site_id" implies when each filter is useful, giving some context for invocation. However, there is no guidance on when to use this tool versus list_service_areas, list_sites, or list_service_area_system_classes, and no mention that both filters can be combined.

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