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

Annotations already declare readOnlyHint and openWorldHint, so the safety profile is covered. The description adds two things annotations cannot: a per-call cost of 30 points and the precedence rule that supplying PNU causes bunji fields to be ignored. Those are material behavioral facts for planning a call.

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 purpose and then the input requirement and cost. No filler or repetition, though the enumeration of ten register types is dense and could arguably be left to the enum.

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 14-parameter lookup with no output schema and read-only annotations, the description covers purpose, required inputs, type-scoping, and cost. It stops short of describing the shape of the returned register records, but the type enumeration and annotations make it usable as-is.

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 already documents all 14 parameters including type-specific fields. The description restates the PNU (19-digit) vs sigunguCd·bjdongCd requirement but adds no format or syntax detail beyond what the schema provides, so baseline 3 applies.

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 (look up) and resource (Korean building register) and enumerates the ten register types matching the `type` enum, so the agent knows exactly what is returned. It does not name any sibling to contrast with, but the resource is distinct enough from tools like registry_realestate_search or land_rt_price to avoid confusion.

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 gives the required input combination (PNU or sigunguCd·bjdongCd) and the address-based path, which is genuine usage context. However, it never says when to prefer this over alternatives such as registry_realestate_search or land_rt_price, so selection guidance is only implied.

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