Look up property (matrikkel) info

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

With no annotations, the description carries the full behavioral burden. It discloses the data source (Kartverket's open address register), the scope (returns identifiers, not ownership), and the limitation (ownership requires a different API). This goes beyond a bare statement and gives the agent a clear picture of what to expect, though it omits details like error handling or rate limits, which keeps it from a 5.

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, no filler. The purpose is front-loaded with the specific identifiers, and the second sentence succinctly covers inputs and the ownership limitation. Every sentence earns its place, making it an exemplary model of concise structure.

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 tool with no required parameters, the description effectively communicates the output and the limitation. However, it doesn't explicitly state that at least one of address or coordinate must be provided, which could lead an agent to call it with no arguments. Given the tool's simplicity and the absence of an output schema, this minor gap prevents a perfect score.

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 all parameters have descriptions. The tool description adds the guidance to 'Give a free-text address or a coordinate,' which reinforces the choice between address and coordinate parameters but doesn't add syntax or constraints beyond what the schema already provides. Per the baseline rule for high coverage, this is a solid 3.

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 action (look up cadastral identifiers), a specific resource (property matrikkel info via Kartverket's open address register), and lists the exact identifiers returned (municipality number, gnr, bnr, festenummer). This clearly differentiates it from sibling tools like search_address, which likely return address components rather than cadastral identifiers.

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 tells the agent how to invoke it ('Give a free-text address or a coordinate') and provides a clear exclusion: 'Full ownership data requires Kartverket's authenticated Matrikkel API.' This implies when NOT to use this tool (when ownership is needed) but doesn't explicitly name an alternative sibling. It gives context but lacks an explicit 'use this instead of X' statement, so it earns a 4 rather than a 5.

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