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

Annotations cover read-only and open-world, but the description adds substantial context beyond them: no account or prop_id required, the exact endpoint, the returned fields, and a crucial caveat that unrecognized addresses still return success:true with a generic market rent and how to detect it. This is genuinely valuable behavioral disclosure.

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-loads the discovery-stage purpose, then routes to siblings, then explains returns, then the caveat. Each sentence earns its place and nothing is padded.

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 the description needn't explain returns, yet it does so helpfully, and it supplies the critical reliability caveat. Nothing an agent needs to call this correctly is missing.

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 baseline is 3, but the description adds meaning by clarifying that a unit number signals a rental inquiry and that no prop_id is required. The address formatting detail is fully carried by the schema, so it stays just above baseline rather than at 5.

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 and resource ('estimate a property's monthly RENT') and explicitly contrasts with the sibling 'beycome_estimate', which handles sale-price estimates. An agent can distinguish this tool from its closest sibling purely from the description.

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 explicit when-to-use ('ONLY for rental inquiries or for properties that have a unit number') and when-not, naming the alternative ('For sale-price estimates, use beycome_estimate'). Routing is unambiguous.

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