list_root_folders

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

With no annotations supplied, the description carries full responsibility for behavior, and it discloses the returned data (root folders, free space, reachability) and the downstream dependency for add_movie. The verb 'List' also implies a read-only operation. It could mention permissions or error behavior, but for a zero-parameter read tool this is sufficient.

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 short sentences with no filler: the first states the operation and output, and the second states the key use case. The most important information is front-loaded, and every sentence 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 simple zero-parameter listing tool with no output schema, the description covers the essential output fields (paths, free space, reachability) and the practical need (add_movie path selection). It does not specify output formatting or edge cases, but those are minor for this tool's complexity.

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 tool has zero parameters, so there are no parameter details for the description to add. The baseline of 4 for zero-parameter tools applies, and the description instead focuses on the output semantics, which is appropriate.

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 uses a specific verb 'List' with a clear resource, 'root folders', and states exactly what information is returned: free space and Radarr reachability. It also distinguishes the tool's purpose by linking it to add_movie, which requires one of these paths. This makes it distinct from sibling list tools like list_movies or get_disk_space.

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 second sentence, 'add_movie needs one of these paths,' explicitly identifies the primary use case and tells an agent to call this tool before add_movie. It does not explicitly exclude alternative tools or state when not to use it, but the resource is unique enough among siblings that no strong exclusion is needed.

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