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

Annotations already declare readOnlyHint=true, so safety is covered. The description adds a genuinely valuable gotcha (default returns active units only) plus the underlying endpoint, but it refers to 'filter_active', a parameter name that does not exist in the schema (the actual parameter is 'active'), which can mislead an agent.

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 short sentences, front-loaded with the resource and its key caveat, then the endpoint. Nothing is padding.

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 9 fully documented optional parameters, no output schema, and a read-only annotation, the description covers the essential default-behavior trap. It omits pagination behavior and sort semantics, which are documented in the schema, so the gap is minor.

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 goes slightly beyond the schema by disclosing that the status filter defaults to active-only, a default the 'active' enum description does not state. It adds little else about the other eight filters.

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 ('List rental units') and previews the returned fields (rent, bedrooms, status), which distinguishes it from doorloop_get_unit. It does not explicitly name the sibling it contrasts with, so it stops short of a 5.

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?

'Without filter_active the API returns active units only' implies when the default behavior applies, which is useful. But there is no explicit when-to-use guidance versus doorloop_get_unit or doorloop_list_properties, and no statement of when not to use it.

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