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

With no annotations, the description carries the full disclosure burden and handles it well by warning that the summary is normalized while raw reports temperature in hundredths of a degree and has multiple ambiguous 'capacity' keys. This prevents an agent from misreading raw values. It does not mention failure modes or explicitly state read-only behavior, but the getter framing makes that reasonably clear.

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 sentences with no wasted words. The primary purpose is front-loaded, and the important raw-vs-summary warning is delivered concisely in the second sentence.

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?

The description lists all return categories, explains the summary/raw distinction, and notes that no automation session is required. Since there is no output schema, this gives an agent enough context to call the tool correctly and interpret results. It does not discuss error cases, but that is not a material gap for a simple status getter.

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 100%, so the baseline is 3; both 'udid' and 'raw' are already documented in the schema. The description adds useful interpretive context about the raw output's unit scaling and capacity-key ambiguity, but it does not add additional parameter format or value guidance beyond what the schema provides.

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 uses a specific verb and resource ('Get battery status of an iOS device') and lists the returned metrics: charge percent, temperature, charging state, battery health, and cycle count. It clearly scopes the tool to iOS, distinguishing it from Android siblings, but it does not explicitly differentiate it from the generic device_battery sibling, so it stops short of a 5.

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 description gives clear invocation context with 'No automation session required', telling the agent it can call this tool directly without session setup. It does not name alternatives such as device_battery or state when not to use this tool, so it lacks the explicit when/when-not guidance needed for a 5.

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