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

With no annotations present, the description carries the burden and does substantial work: it lists what is returned (reference, location, address, municipality, area, land use, outline) and hedges availability with 'when the official source provides them'. It also discloses the crop-summary truncation and where the complete data lives. It stops short of stating error behavior when a lookup fails or the parcel is not found, which is the remaining gap for a lookup 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?

The most important facts (lookup mode, return fields, sibling routing, UK restriction) are front-loaded in the first three sentences. The trailing enumeration of 31 country codes is bulky and partly duplicative of the enum, though it does add human-readable names the enum lacks. A tighter version would trim the code list or move it to a schema-level note.

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?

There is no output schema and no annotations, but the description fully compensates by enumerating return fields, qualifying when optional fields like the outline and crop summary appear, and routing to the sibling that returns the expanded subparcel list. Nothing an agent needs to call this correctly or interpret the result is missing.

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%, so the baseline is 3, and the description adds meaning on top: it spells out the country-code-to-name mapping (the schema only lists codes, aside from a note on PV/NA), restates the reference-vs-coordinates exclusivity, and notes that country may be omitted due to format/point detection. The language parameter's effect is only covered in the schema ('Language of crop names'), so the description contributes no additional semantics there.

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 verb and resource ('Look up a cadastral parcel') and immediately bounds the scope: 29 European countries, lookup by official reference or WGS84 coordinates. It explicitly distinguishes itself from the closest sibling by naming get_parcel_subparcels as the tool for the full part list, so an agent can route correctly without opening either schema.

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?

It gives concrete selection conditions: use the reference when you have one, coordinates otherwise, and defer to get_parcel_subparcels when the full subparcel list with outlines is needed. It also flags an exclusion ('United Kingdom: coordinates only') and explains that the country param can be omitted because it is auto-detected, which is the main usage ambiguity for this tool.

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