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

Annotations cover safety hints, but the description adds substantial behavioral context beyond them: the exact JSON return shape, field meanings (faceUp/faceDown, non_flat_orientation), the read-only lock limitation, and the 'no HID available' failure mode on iOS 17.x/no-tunnel. This is exactly the kind of detail an agent needs.

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?

Four sentences, each earning its place: purpose/benefit first, then return format, then a key limitation, then an error condition. No filler, front-loaded, easy to scan.

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 read tool with one parameter, rich annotations, and no output schema, the description fully covers what the agent needs: what it returns, how to interpret fields, what it cannot do, and when it fails. Nothing material 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?

Only one parameter (udid) and schema coverage is 100%, so the schema already fully documents it. The description adds no parameter-specific meaning, which is acceptable given the baseline of 3 for high schema coverage.

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+resource ('Read the device orientation and whether the iOS orientation lock is on') and immediately distinguishes itself from session-based siblings with 'without touching the screen (no automation session needed)'. The scope and mechanism are unambiguous.

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?

Gives clear context: use when no automation session is desired, and notes the lock cannot be changed here. It does not name specific alternative tools or state when *not* to use it, but the primary usage condition is explicit.

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