phone_key

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

With no annotations, the description carries the full burden. It discloses the experimental status and the environment requirements, which is real value beyond structured fields, but it doesn't say what state is required (active session, focused app) or what an error or success looks like.

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 short clauses, with the EXPERIMENTAL warning and environment requirement front-loaded before the action. Nothing is redundant, though the sentence fragments could be tightened into a single statement.

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 one-parameter tool with no annotations or output schema, the description covers prerequisites and valid inputs but leaves out the runtime state needed for it to succeed and any indication of failure modes. Adequate to attempt the call, not to call it reliably.

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 coverage is 0% and the schema types 'key' only as a plain string, so the description's enumeration of the six valid key values is the only source of that constraint. It stops short of saying whether 'key' is required or what the default is when omitted (required is 0).

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 ('Press a key') and the exact key set (return, delete, up, down, left, right), and the iPhone Mirroring prerequisite makes clear it targets the mirrored iPhone rather than the Mac. It doesn't explicitly name mac_key or browser_press_key as alternatives, but the phone scope is discernible.

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 prerequisites (iPhone Mirroring running, python3 with pyobjc) tell the agent when the tool can work at all, which is genuinely useful context. It never says when to choose this over mac_key or browser_press_key, nor what happens if mirroring is not active, so usage is only implied by the sibling naming.

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