list-folders

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

With no annotations, the description carries the full burden. It discloses what the tool returns (each folder's title, parent folder, album count, subfolder count), implying a read-only query. It does not explicitly state 'does not modify anything', but the 'Returns' phrasing and list-oriented purpose make the behavior sufficiently clear.

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 three concise sentences, each earning its place: when to use, what it returns, and when not to use. It is front-loaded with the usage intent and contains no filler words.

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 tool with one optional parameter, an output schema, and clear sibling context, the description covers purpose, usage, return content, and exclusions. It is complete enough for an agent to invoke it correctly without further information.

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% (the 'library' parameter is described in the schema). The description does not add new meaning beyond mentioning 'library's folder hierarchy', which is already implied. Baseline 3 applies as schema does the heavy lifting.

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 clearly states the tool lists the library's folder hierarchy, specifying the containers (folders) that hold albums and subfolders. It distinguishes from siblings like list-albums and library-info by specifying what this tool does not return, ensuring no ambiguity.

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?

Explicit 'Use when' and 'Do not use when' sections provide clear context and explicitly name alternatives (list-albums, library-info). This goes beyond mere implication, giving the agent direct decision rules.

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