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

Beyond the annotations (idempotent, non-destructive, closed-world), the description discloses real behavioral traits: it works despite the OS orientation lock, returns {orientation, non_flat_orientation, locked} as the device reports it, that portraitUpsideDown may be a no-op on iPhone Home screens, and the exact error string on unsupported versions. This is unusually rich transparency for a mutation tool.

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?

Front-loaded with the core action and the key differentiator, followed by enum, return shape, and caveats in a tight sequence. Almost every clause earns its place; the only mild redundancy is re-listing enum values already present in the schema.

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?

With no output schema and only two params, the description compensates fully: it documents the response object, version-dependent failure modes, and a surprising platform quirk. Nothing an agent needs to call or interpret this tool correctly 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% and the enum values are already enumerated in the schema, so the description's restatement of the orientation values adds little beyond confirming the accepted set. The 'udid' parameter is not discussed at all. Baseline 3 applies when the schema carries the parameter burden.

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 ('Put the device in an exact orientation') and immediately distinguishes itself from session-based rotation siblings with 'no automation session needed; works even while the iOS orientation lock is on'. An agent can tell it apart from ios_orientation/ios_rotate without opening either schema.

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 for when this tool is the right choice (no automation session, orientation lock on) and a failure condition ('no HID available' on iOS 17.x / no-tunnel). It does not explicitly name a sibling alternative or say when to prefer ios_orientation instead, so it stops short of a 5.

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