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

With no annotations to lean on, the description carries the full burden and delivers: discloses idempotency ('succeeds silently if the directory already exists'), failure mode ('fails with the shell error if the parent is read-only'), and filesystem write constraints. Only minor gap is no explicit statement of the success return value, though 'succeeds silently' partially implies it.

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 earning its place: core action first, sibling differentiation second, behavioral nuances last. No filler, no restating of the schema's parameter doc.

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 low-complexity tool (2 simple string params, fully schema-documented, no output schema), the description covers everything an agent needs: what it does, where it can write, that it is idempotent, and how it fails. Nothing essential is missing.

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%, setting the baseline at 3, but the description adds meaning beyond it: the mkdir -p behavior clarifies that remotePath may be a nested path with nonexistent parents, and the writable-locations note helps the agent generate or validate valid remotePath values.

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 the device') with an explicit behavioral qualifier ('including any missing parents (mkdir -p)'). Names the iOS counterpart (ios_file_mkdir), which immediately disambiguates it from the large device_file_*/ios_file_* sibling families.

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?

Names the direct alternative ('Counterpart of ios_file_mkdir'), implying platform selection between device and iOS variants, and adds practical deployment guidance by flagging that most of the filesystem is read-only outside /sdcard and /data/local/tmp. Stops short of an explicit when-to-use/when-not-to-use directive, so it misses the top score.

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