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

Annotations already declare readOnlyHint and openWorldHint, yet the description adds substantive non-schema context: pagination size, total-count return, x402 payment rails (Base, Solana, Arc), the $0.002-per-successful-call cost, and that failed calls are not charged. That charging-failure detail is genuinely useful behavioral disclosure beyond the annotations.

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?

Purpose and scope are front-loaded in the first clause, the field enumeration is compact, and the separate pricing sentence covers cost without padding. No filler sentences; each 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 did not need spelling out (the field list is mild redundancy but helpful). Annotations cover the safety profile and the description covers cost and pagination. Only gaps are behavior on zero results or invalid ZIP/placeId, which are minor for a read-only listing tool.

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 the baseline is 3, but the description adds the meaningful alternative-path relationship (ZIP alone, or city + Census place ID) and reinforces that state is required. That clarifies how the 5 parameters combine in a way the individual field descriptions only hint at.

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 verb+resource (retrieves RE/MAX US for-sale listings by ZIP or city place ID) and enumerates returned fields, so the agent knows exactly what it gets. The source domain (remax.com) implicitly differentiates it from realestate_zillow or realestate_redfin, but no sibling is explicitly named as an alternative.

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?

Gives the input path ('give zip, or city + placeId') and page size ('24 per page plus the total count'), which implies usage. It never states when to prefer this over the many sibling real-estate listing tools, nor any failure/empty-result conditions.

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