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

Annotations already declare readOnlyHint, idempotentHint, non-destructive and closed-world, so the safety profile needs no restating. The description adds real value beyond them: the data source (MOLIT reported contracts), the geographic scope (nationwide plus Seoul), and the exact metric set returned. It stops short of noting datapoints like reporting lag or whether renewed-lease figures are seasonally adjusted.

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 with no filler: the first front-loads what comes back, the second front-loads the use case. The metric list is dense but every element is distinct information.

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 parameters and no output schema, the description must carry the return content itself, and it does — enumerating the metrics and the geographic scope. It is largely sufficient for an agent to decide whether to call it, with the main residual gap being no explicit routing guidance against the median/trend/compare siblings.

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?

Zero parameters and 100% schema coverage, so there is nothing for the description to compensate for. The baseline of 4 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?

Names the concrete resource (reported housing contracts from MOLIT) and enumerates the specific metrics returned: median monthly rent, jeonse deposit, apartment sale price by home type, renewal increases, and jeonse-to-sale ratio. Scope (nationwide and Seoul) is explicit. It doesn't explicitly contrast itself with housing_median or housing_trend, but 'summary' and 'quick overview' do signal an aggregated snapshot versus those siblings.

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 single guidance sentence — 'Use it for a quick overview of the Korean rental market' — gives the intended context, but there are no exclusions and no named alternatives. With three closely related siblings (housing_compare, housing_median, housing_trend) an agent must infer on its own when to reach for this one instead of them.

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