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

With no annotations provided, the description carries the full burden. It discloses a key behavioral trait: 'Does NOT require an automation session.' It also implies a read-only status check. However, it does not describe the return format or error behavior, which would be helpful but not critical for a simple status 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?

The description is two concise sentences, front-loaded with the core purpose and output, followed by usage guidance and a key constraint. Every sentence earns its place with no fluff.

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 one-parameter status tool with no output schema, the description covers purpose, usage context, and a key behavioral trait (no session). It could specify the return format, but the absence of an output schema makes that less critical. Overall, it provides enough for an agent to decide when to call it and what to expect.

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?

The schema covers the single parameter 'udid' with a description ('iOS device UDID'). The tool description adds no extra semantic detail about the parameter, so it remains at the baseline 3 for a fully documented schema.

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?

The description states a specific verb ('Report') and a clear resource: HID input availability and display size on an iOS device. It explicitly differentiates from the sibling *_hid and session-backed ios_* tools, making its purpose unmistakable.

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?

It gives direct guidance: 'Use to decide between the *_hid tools and the session-backed ios_* tools.' This tells the agent exactly when to call this tool and implies the alternative (session-backed tools when HID is not available). Also notes that no automation session is needed, further clarifying usage context.

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