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

Annotations already cover the safety profile (readOnly, idempotent, non-destructive, closed-world), so the bar is lower. The description still adds value by disclosing that results come only from published territories and reflect visitor routing, i.e. unpublished edits will not affect the answer — a non-obvious behavioral constraint an agent should know.

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 single tight sentence with no filler, and the key scoping constraint (PUBLISHED) is front-loaded. It loses a point only because the sentence is a fragment and the object it explains is stated indirectly.

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 3-parameter, read-only lookup with full schema coverage and no output schema, the description supplies the essential framing: what is being explained, why the answer has rationale, and which territory state it derives from. Only the shape of the returned explanation is left unstated, which is acceptable here.

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 lat, lng and the conditional postcode rule are already documented in the schema (including the warning that postcode rules cannot match without postcode). The description adds no parameter-level meaning beyond that, so the baseline of 3 applies.

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 states a specific question it answers ('Which dealer owns a point, and why') and pins the data source to PUBLISHED territories. It reads clearly as a query/explanation tool distinct from list_territories or publish_territories, though it never names a sibling to route against.

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?

'Answered from the PUBLISHED territories, exactly as a visitor there would be routed' implies when to reach for it (visitor-facing truth, not draft config), which is meaningful context for a repo full of propose/apply/publish tools. But there is no explicit when-not or named alternative, so the selection guidance is left to inference.

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