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

Annotations already declare readOnly, idempotent, closed-world and non-destructive, so safety is covered. The description adds genuinely new behavioral context: counts derive from county records and are 'never estimates', and results carry an as-of date, which sets accuracy and freshness expectations beyond structured fields.

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 sentences, front-loaded with the core count action; the buyer-trade list is long but informative. Slightly run-on structure keeps it from a 5, but no sentence is wasted.

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 no output schema, the description usefully sketches the return shape (per-buyer-trade counts plus as-of date) and data provenance. The remaining gap is that all parameters are optional and the description never says which locator is required or what happens with no arguments.

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% and each parameter (zip, town, state, county) is documented there, so baseline 3 applies. The description restates county/town/ZIP but omits the state enum and the precedence between overlapping locators, adding nothing the schema lacks.

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 (count parcels tracked) and the geographic grains (county, town, ZIP), plus the breakdown dimension (buyer trade) and as-of date. It never names the sibling it is contrasted with (find_parcels, check_parcel, list_coverage), so the aggregate-vs-list distinction must be inferred.

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?

Usage is only implied: 'How many parcels...' signals a counting/summary call rather than a parcel listing. There is no explicit when-to-use/when-not guidance against find_parcels, check_parcel, or list_coverage, and no statement about what to do when an area has no coverage.

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