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

Annotations already declare readOnlyHint, idempotentHint, and destructiveHint=false, so the safety profile is covered. The description adds a genuine prerequisite disclosure not present in annotations — that no automation session is needed — which materially changes how an agent should sequence the call.

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?

Two short sentences, front-loaded with the verb and resource, with the session-prerequisite caveat appended. No filler and nothing redundant.

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 read-only, idempotent, single-parameter tool with full annotation coverage and a fully described schema, the definition supplies what is needed: what it returns and that no session is required. The absence of any note on output shape is a minor gap since there is no output schema.

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 single udid parameter is fully documented in the schema, so the baseline is 3. The description adds no format, targeting, or constraint detail about udid beyond what the schema already states.

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 (get) and resource (device diagnostics) and enumerates the categories returned (battery, HDMI, WiFi) on an iOS device. It is clear on its own, but it does not distinguish itself from overlapping siblings such as ios_battery, ios_device_info, or ios_performance_snapshot.

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?

'No automation session required' gives one real usage cue — the agent knows it can call this without an active session, which is valuable given the many session-scoped siblings. However, there is no guidance on when to prefer this over ios_battery or ios_device_info, so the when-to-use picture is only implied.

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