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

Annotations already declare idempotentHint=true and destructiveHint=false, so the description isn't carrying the safety burden alone. It still adds genuine context the annotations don't: the reply distinguishes `created` vs `existed` instead of failing, and it recursively creates parents. No permission or error-path detail beyond that, so not 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?

Two tight sentences; the core action leads, the idempotency benefit is front-loaded as the reason it saves a check, and the sibling reference closes it out. 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?

For a 3-param, no-output-schema filesystem tool with full schema coverage and clear annotations, the description covers what's needed to call it correctly, including the idempotent return distinction. Only minor gaps remain, such as what errors occur on invalid paths or device unavailability.

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%, so the schema already explains udid, bundleId (with its container semantics) and remotePath. The description only re-references bundleId via 'Same bundleId root selection as ios_file_list', adding no syntax or value detail beyond the schema. Baseline 3 applies.

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 directory on an iOS device') and adds the recursive scope ('parent directories included'), which is a meaningful behavioral detail rather than a restatement of the name. It also points at sibling ios_file_list for the bundleId root-selection convention, giving an anchor for distinguishing it from other file tools.

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 tells the agent it can call this without a prior existence check ('staging a temp folder needs no existence check first'), which is real usage guidance. It stops short of naming alternatives or when-not-to-use conditions relative to the other ios_file_* / device_file_* siblings.

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