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

Annotations already declare readOnlyHint=false, destructiveHint=false, and idempotentHint=false, so the description's lower bar is met by adding two pieces of real context: the operation is 'Free' (cost behavior not in any structured field) and parentId must be a top-level folder, implying limited nesting depth. It still omits what happens on duplicate names, whether a failed create charges anything, and what identifier comes back.

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 very short sentences, front-loaded with the action and resource, then the optional parameter, then cost. Nothing is padded and the ordering matches how an agent would need the information.

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 2-parameter creation tool with annotations covering the safety profile, the description is close to sufficient, and 'Free' usefully covers cost. However, with no output schema, the agent is never told that a folder id is returned (which it needs for parentId on subsequent calls), and the required 'name' parameter's constraints are absent from both description and schema.

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 only 50%: the 'name' parameter has no description anywhere, and the parentId schema description is nearly verbatim what the tool description repeats ('top-level folder id to put it inside'). The description therefore adds no meaning beyond the schema and leaves the one undocumented parameter (name: length limit? uniqueness? allowed characters?) completely unspecified.

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 ('Create a new folder') scoped to 'your Switch library', which is enough to separate it from rename_folder, delete_my_folder, and list_my_folders in the sibling list without reading their schemas. It stops short of 5 because it never names the sibling tools it sits alongside in that folder family.

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?

There is no explicit when-to-use or when-not-to-use guidance; the agent must infer that this is the creation counterpart to rename/delete/list. The only usage-like signal is the parentId hint that it should be a 'top-level folder id', which constrains nesting but is not stated as a rule (e.g. 'folders cannot be nested more than one level').

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