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

Annotations already cover readOnly, idempotent, non-destructive and openWorld=false, and the description goes further with a 30 requests/IP/minute rate limit, the 2-degree-per-side box cap (a constraint the schema does not express), and a no-API-key access note. It stops short of saying whether the returned count is exact or an estimate, which matters for a tool named 'preview'.

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?

Three short sentences, front-loaded with the access/cost fact, then capability, then hard limits. No filler and nothing repeated from the schema or annotations.

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 still names all three return components, and it covers cost, access, rate limits and box size for a simple four-parameter read. Minor gaps remain on edge cases such as antimeridian-crossing boxes and count accuracy.

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 100% and each bound is documented with EPSG:4326 semantics, so the schema carries most of the load and the baseline is 3. The description adds real meaning by framing the four numbers as a bounding box and constraining each side to at most 2 degrees, which the schema's per-value min/max does not convey.

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 and resource ('Counts the parcels inside a bounding box') plus its three outputs: parcel count, touched counties, and a $49-extract fit verdict. It is clearly distinguishable from siblings like find_parcels_in_polygon or find_parcels_in_radius because the scope is explicitly a bounding box.

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 '$49 extract of up to 5,000 parcels' fit check and 'Free, no API key' imply this is the cheap pre-quote step before calling find_parcels_* or get_pricing, but the description never names those alternatives or states exclusions explicitly. Usage is inferable rather than prescribed.

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