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

Annotations already declare readOnlyHint, idempotentHint, destructiveHint=false and openWorldHint=false, so safety is covered. The description adds real behavioral detail beyond that: what an empty prefix returns (top-level folders, including merchant-created ones) and what each listed file carries (key, file name, size). It stops short of stating pagination or ordering, which keeps it from 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?

Three tight sentences, front-loaded with what is listed, then the prefix behavior, then sibling routing. No restated field names and no filler.

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 an output schema present, return values need not be spelled out, yet the description still previews the per-file fields. Combined with full schema coverage and complete annotations, an agent has everything needed to call this correctly.

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 100% and already documents both parameters, so the baseline is 3. The description earns above baseline by explaining the meaning of an empty prefix versus a folder prefix and the consequence for the returned shape — semantics the schema only gestures at with an example.

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?

Opens with a specific verb+resource statement ('The workspace's uploaded documents and folders') and then explains the two listing modes. It names the sibling tools (searchDocuments, readDocument) it is not, so an agent can distinguish it without opening another schema.

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?

Explicitly routes the agent: use searchDocuments for document content and readDocument with a key to read one in full. The prefix semantics ('a folder such as contract/ lists its files') tell the agent exactly which invocation to use for which intent.

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