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

Annotations already mark this as read-only, idempotent, and non-destructive. The description adds useful behavioral context beyond those hints: it names the data sources, the computed outputs including remaining buildable area after setbacks, and the ordering constraint relative to match_plans_to_lot. It does not significantly contradict or omit safety-relevant behavior.

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 substantive sentences plus a concrete example, with the core purpose and output list front-loaded before usage guidance. No filler or repetition beyond the intentional coverage emphasis.

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?

No output schema exists, but the description compensates by listing the key returned fields and giving a concrete example. The main gap is that it does not explicitly state that at least one of address or apn should be provided, especially since the input schema marks no parameters as required. Overall it is still highly usable.

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%, so the schema fully documents apn, county, and address with formats and examples. The description does not add much parameter meaning beyond the schema—it provides the same example address and implies address/APN are the lookup keys, but the schema already handles this. Baseline 3 is appropriate.

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 uses a specific verb ('resolve') with a clear resource (street address or APN to the lot itself) and enumerates the computed outputs. It also distinguishes itself from match_plans_to_lot and ties directly to the ADU use case, so an agent can select it accurately.

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 explicitly says to use this tool before answering 'can I build an ADU here' and before match_plans_to_lot. It also states the coverage limitation (Los Angeles County and San Diego County only), which tells the agent when not to use it.

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