libraries

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

Since no annotations are provided, the description carries the behavioral burden. It clarifies that only top-level libraries are returned, avoiding confusion with nested items. The verb 'List' implies a read-only, non-destructive operation. No side effects or permissions are mentioned, but none are needed for such a straightforward listing.

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?

The description is a single, front-loaded sentence. It includes a specific verb, the target resource, and clarifying examples without any filler. Every word earns its place.

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 no-argument tool with an output schema present, the description is functionally complete. It defines the operation and scope clearly. It could optionally mention that the returned libraries can be used as inputs to search or info, but this is not necessary for correct invocation.

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?

The input schema has zero parameters, and schema description coverage is 100% (vacuously). Per the baseline for 0-parameter tools, a score of 4 is appropriate because there are no parameter semantics to add.

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 states a specific verb ('List') and a clear resource ('top-level media libraries') with illustrative examples (Movies, TV Shows). It is immediately distinguishable from sibling tools like search, info, sessions, and next_up, which all describe different operations.

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?

The description makes it clear that this tool is used when you need the list of top-level media libraries. There is no explicit mention of alternatives or when-not-to-use, but the imperative phrasing and resource specificity provide clear context without ambiguity.

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