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

Annotations already declare the tool read-only, idempotent, and non-destructive. The description adds two valuable behaviors: returns 404 on no match and has 24h upstream caching. These give context beyond the annotations without contradiction.

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 concise sentences, each adds new information, no redundancy, and the main purpose is front-loaded in the first 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?

For a single-parameter retrieval tool, the description covers the purpose, id source, a specific error response, and caching. No output schema is present, but "full detail" is implicit; a bit more about the response content would be helpful, yet the description is adequate for the simplicity of the 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 for the single parameter is 100%, so the schema already documents the parameter fully. The description adds value by explaining the id is the RentCast id from prior endpoints, reinforcing the semantic source and context of the parameter.

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?

The description clearly states the tool fetches full detail for a single property record by RentCast id, which differentiates it from sibling search/AVM tools that return lists or values. The phrasing "single property record" and "keyed by its RentCast id" immediately convey the specific verb and resource.

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?

It explains that the id is the same as returned on every search_properties, avm_value, avm_rent, and listings record, implying usage after those calls. It also implies using this tool when full detail is needed. However, it does not explicitly state when NOT to use it or name direct alternatives.

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