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

With no annotations, the description discloses key behaviors: device-side copy (bytes never travel), directories are refused with a rationale, and a recommended fallback. It does not mention overwrite behavior, but the disclosed traits are substantive beyond schema.

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 sentences each earn their place: defining the operation, providing usage preference, and explaining a restriction with an alternative. No redundancy or 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?

The description effectively covers purpose, behavior, limitations, and alternatives for a file copy tool. It lacks explicit return/error details, but given the schema and sibling context, the description is largely complete for selection and invocation.

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% with descriptive parameter text, so the description adds little parameter-specific detail. It adds context about 'same root' and directory refusal, but this applies to the operation rather than individual parameters.

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 'Duplicate ONE file to another path on an iOS device' with a specific verb and resource, and explicitly contrasts with pull-then-push and ios_file_list, distinguishing it from sibling file operations.

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?

It explicitly says 'prefer this over pull-then-push when both paths are in the same root' and describes when to use ios_file_list instead for directory trees, providing clear when-to-use and alternative guidance.

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