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

Beyond readOnlyHint/openWorldHint, the description discloses what annotations cannot: a per-call price ($0.002 USDC), the payment rail (x402 on Base, Solana or Arc), and that failed calls are not charged. It also caps the result set at the first page of roughly 20 listings, which materially affects how an agent plans requests.

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?

Front-loaded with what the tool returns, then the pagination caveat, then cost. Efficient overall, though the field enumeration is a long comma chain that partially duplicates the output schema and lengthens the opening sentence.

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 an output schema present, listing return fields is redundant but harmless; the description still supplies the non-obvious essentials (page limit, pricing, payment rails). Minor omissions remain, such as behavior on an invalid area path or whether any authentication beyond payment is required.

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% and the schema already documents the area path format and the for-sale/to-rent values, so the description only restates them at a high level ("for sale or to rent"). It adds no format, default, or validation detail beyond the structured data, so the baseline of 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+resource+source: South African property listings from Property24 for an area, and enumerates the returned fields (headline, suburb, price in rand, bedrooms, bathrooms, parking, floor size, URL). The portal and country scope let an agent distinguish it from the many other real-estate siblings (rightmove, zoopla, hemnet, zillow) without opening any 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?

Clear operating context: results are the first page only (about 20 listings) and cover either for-sale or to-rent via the deal parameter. That '~20 results, no pagination' note implicitly tells an agent when this tool is insufficient, but it never names an alternative sibling for broader or other-country searches.

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