List Android devices

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

Beyond the annotations (readOnlyHint=true, etc.), the description adds meaningful behavioral context: devices in 'unauthorized' or 'offline' states surface here, the tool returns an empty list rather than erroring when nothing is plugged in, and detailed mode costs an extra adb round trip. It also explains the significance of the 'unauthorized' state and on-screen prompt, enriching the agent's understanding without contradicting annotations.

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 long but highly organized with clear sections (Description, Args, Returns, Examples, Error Handling). Every sentence serves a purpose: it explains core behavior, usage timing, parameter semantics, return shape, and failure modes. It is front-loaded with the most critical 'call this first' guidance, making it efficient for quick scanning.

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 is self-contained and comprehensive. It defines the return object structure even though no output schema exists, covers error handling (empty list, unauthorized state), and explains when to use the tool in the broader workflow. The annotations handle safety/profile, so the description covers all other needed context for an agent to invoke it correctly.

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%, but the description adds significant value beyond the schema. For 'detailed' it lists exactly which properties are queried (Android version, SDK level, screen size, density, rotation) and notes the performance cost. For 'response_format' it clarifies the human-readable vs machine-readable tradeoff. The Args section is rich and directly useful for parameter selection.

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 opens with 'List every Android device and emulator currently visible to adb, with model, Android version and screen geometry,' a specific verb+resource+scope statement. It clearly distinguishes this tool from siblings by focusing on device enumeration and serial discovery, explicitly contrasting with tools like android_logcat.

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 explicit when-to-use guidance: 'Call this first in any session: other tools need a serial when more than one device is attached.' It also provides a when-not-to-use example with a named alternative: 'Don't use when: you already have a serial and just want app logs (use android_logcat).' This fully covers usage context and exclusions.

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