list_props

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

Annotations already declare readOnlyHint=true, so the description's job is lighter, and it still adds real value by describing what each mode returns (module/builder listing vs. a usage guide). No information on format or size of the returned guide, which keeps it below a 5.

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?

Two tight sentences with zero filler, front-loading the resource and then the mode behavior in parallel structure that maps directly onto the one parameter's two states.

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?

One optional parameter, no output schema, read-only annotation — the description covers both call paths and their returns, which is nearly everything needed. The only gap is that valid `module` string values are never characterized.

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 0% — `module` is a bare string — so the description must carry the meaning, and it does: it defines the semantics of both the absent and present states. It stops short of saying where valid module names come from or their format, but the 'without module returns the modules' phrasing implicitly answers discovery.

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 ('Browse') and resource ('low-poly prop library') and enumerates the content categories (people, furniture, places, vehicles). An agent can tell this is a discovery/listing tool rather than a renderer like preview_prop, though the sibling relationship is only implied.

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?

Clearly explains the two calling modes: omit `module` to get modules and their builders, supply `module` to get that module's full usage guide. That is effectively when-to-use guidance for the single parameter, but it doesn't contrast with alternatives such as preview_prop.

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