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

No annotations exist, so the description carries the full burden and does so: it discloses the billing model (one API call, charged only when a price comes back), the exact error codes and their non-charging behavior, and the valuation caveat that buildings inside the parcel are not priced (price_note). This is above-and-beyond behavioral disclosure for a tool with zero annotation coverage.

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?

Nearly every clause earns its place (billing, supported regions, excluded property types, error codes), but the front-loading is off: the first sentence leads with plan/billing policy rather than the tool's purpose, which only arrives in the second sentence. The heavy parenthetical nesting also makes it harder to scan than it needs to be.

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 and no annotations, the description must cover return semantics, and it does name the meaningful response fields (crop_prices per crop group with sales counts, zone_prices.rural, price_note). It leaves the full response shape and the error-payload format only partially described, but an agent has enough to predict outcomes and interpret pricing correctly.

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 both parameters are already documented in the schema, including the country enum and the ES/PV/NA restriction, so the baseline is 3. The description reinforces the country constraint but adds no new syntax or format details for 'reference' beyond calling it a cadastral reference.

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 names a specific resource and scope: agricultural/rural land pricing in Spain (ES, PV, NA), returning crop_prices in EUR per hectare and zone_prices.rural. It also draws a sharp boundary by stating that housing, industrial and other non-agricultural property is out of scope, which lets an agent distinguish it from parcel/agriculture siblings without inspecting schemas.

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?

Use conditions are explicit and concrete: rural land only, three supported country codes, paid plan required, and the specific failure paths (MKT_001 for non-agricultural property, missing price, or other countries; KEY_PLAN_001 for Free-plan keys). It stops short of naming which sibling tool an agent should call instead for urban or non-agricultural valuation, so 4 rather than 5.

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