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

With no annotations provided, the description carries the full burden. It discloses key behaviors: recursive copying and the within-device constraint. It does not mention overwrite semantics, permissions, or error conditions, but for a straightforward copy operation these are secondary and the most important behavioral traits are covered.

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 sentences with zero wasted words. It front-loads the core action, then clarifies the scope (within device) and directs to the correct alternatives for host transfers. Highly efficient and structured.

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 3-parameter tool with no output schema, the description covers the essential context: what it does, where it operates, and how to differentiate it from related tools. It omits details like overwrite behavior, but that is not critical for correct invocation. The description is sufficiently complete for an agent to use it appropriately.

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% (each parameter has a clear description: 'Absolute destination path', 'Device serial number (UDID)', 'Absolute path of the source file or directory'). The description adds the recursive behavior but does not clarify parameter meanings beyond the schema. Baseline 3 is appropriate.

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 states a specific verb and resource ('Copy a file or directory on the device'), clarifies recursive behavior, and distinguishes it from the iOS counterpart (ios_file_copy) and from host-transfer tools (device_file_pull/push). An agent can immediately understand what this tool does and how it differs from its siblings.

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 description explicitly directs users to device_file_pull/push for host transfers, and names ios_file_copy as the counterpart, which clarifies when to use this tool. However, it does not mention other device file operations like move or delete as alternatives, so the guidance is strong but not exhaustive.

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