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

Annotations already declare readOnlyHint=true and openWorldHint=true, so the safe read-only profile is covered. The description adds genuine context beyond annotations: only ACTIVE zones are returned, and address input is looked up and cached. It omits the return shape or pagination, so it's useful but not rich.

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 front-loaded sentence that leads with what the tool returns and then explains the input modes. No filler, though the two clauses are slightly compressed.

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 read-only geospatial lookup with no output schema, the description covers purpose and inputs but doesn't indicate the response contents (e.g., zone list/names) or behavior when a place falls in no zone. Adequate but leaves a gap.

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 coverage is 0%, so the description carries the burden and partially compensates: it clarifies that address is geocoded and cached and that lat+lng is an alternative to it, establishing address-vs-coordinates semantics. It adds no format or expected-range detail for any of the three parameters.

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 resource (active service zones) and the relation it answers (which contain a place), which distinguishes it from list_service_zones (all zones) and geocode_address. It doesn't name a sibling explicitly, but the verb+resource is concrete and unambiguous.

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 gives two input modes (address or lat+lng) but never states when to prefer this tool over list_service_zones, nearest_technicians, or reverse_geocode. Usage is implied by the purpose rather than spelled out with conditions or exclusions.

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