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

Annotations already declare this a safe, idempotent read, so safety needs no restating. The description adds genuinely useful context: the underlying data source (closed sales), the statistical method (interquartile middle half), and an interpretive caveat that the result is not an appraisal — which tells the agent how to present the number.

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 dense sentences with zero filler, front-loading the most important framing ("Arithmetic, not a price opinion") before the method and the routing instruction. Every clause carries 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?

An output schema exists so return values need no explanation, and annotations cover the safety profile. The description supplies method, scope, fallback awareness, and an alternative-tool route — nothing an agent needs in order to call this correctly is absent.

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 four parameters including the sub-five-sales fallback to island-wide. The description's "for a complex, or for attached or detached homes island-wide" largely restates that schema split rather than adding new semantics, so the 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?

Names a specific computation and resource: the 25th–75th percentile of closed-sale price per square foot multiplied by heated square feet. It also explicitly distinguishes itself from the CMA workflow by routing agents to request_contact, so an agent can place it among siblings without opening the 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?

"Arithmetic, not a price opinion" plus "For a real CMA, send the person to request_contact" gives an explicit boundary and names the alternative tool. It never states the positive trigger (use this when a client wants a quick ballpark figure) in so many words, so it stops short of full when/when-not coverage.

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