device_info

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

Annotations already provide readOnlyHint=true, so the safety profile is covered. The description adds the specific fields returned (model, version, screen size, SDK, battery), which is useful but doesn't disclose potential latency, failure modes with multiple connected devices, or behavior when serial is omitted and no device is connected.

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?

Single sentence, perfectly sized, front-loaded with the action and resource, then specific detail fields. Zero waste.

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?

Tool has one optional parameter fully documented in schema, clear annotations, and an output schema. The description lists the key data returned. It could mention behavior when no device is connected or when multiple devices exist, but for a read-only info tool this is largely sufficient.

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% — the serial parameter is documented as device serial number with the fallback behavior to the only connected device. The description adds no additional parameter semantics beyond what the schema already states. Baseline 3 is appropriate here.

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?

Clear verb+resource: 'Get detailed info about a device' with specific fields listed (model, Android version, screen size, SDK level, battery level). It distinguishes from siblings since no other tool retrieves device metadata, though it doesn't explicitly name an alternative.

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 doesn't explicitly say when to use this tool versus alternatives. However, its read-only information retrieval purpose is implicitly clear given the sibling set (all other tools perform actions or sessions). No exclusion criteria or alternative tools mentioned.

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