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

Annotations already declare readOnlyHint=true and openWorldHint=false, so the description needn't restate safety. It does add two pieces of behavior beyond the annotations: the Pro-plan gating (a real precondition an agent must handle) and the shape of returned entries (paths plus per-folder file counts). It omits ordering, pagination, and whether folders are flat or hierarchical, keeping 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?

A single sentence with no filler; the resource is named first and the returned fields and plan constraint follow immediately. Nothing is redundant with the title or annotations.

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?

With no input schema and no output schema, the description carries the burden of saying what comes back, and it does so at a high level (paths and file counts). It is nearly complete for a simple read-only list tool, though it leaves folder hierarchy and any result-size limits for the agent to discover.

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 takes zero parameters, so the schema has nothing to document and the baseline of 4 applies. The description correctly introduces no parameter concepts that would need explaining.

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 gives a specific verb and resource ("Lists your folders") and adds what each entry contains ("paths and how many files each one holds"), which goes beyond the bare name. It does not explicitly distinguish itself from siblings like list_files or search_files, but the noun makes the resource scope unambiguous.

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 parenthetical "(Pro feature)" signals a plan prerequisite, which is useful context for an agent deciding whether to call it. However, there is no explicit when-to-use versus list_files, no statement about when the tool is not appropriate, and no fallback behavior described if the account is not Pro.

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