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

With no annotations, the description carries the full burden, but it does add a valuable behavioral detail: spaces and shell-special characters are escaped so the literal text is entered. However, it does not disclose other important traits such as device targeting (serial), required permissions, or whether it waits for the field to be ready.

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 sentences, front-loaded with the core action, followed by a useful escaping note. No wasted words; every sentence earns its place.

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 adb tool with an output schema (so return values need no explanation), the description is adequate but incomplete. It omits any mention of the serial parameter and lacks context about focusing fields or usage in multi-device scenarios, which matters in a suite with many sibling tools.

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 0%, so the description must compensate. It implicitly covers the 'value' parameter ('type a string'), but says nothing about the optional 'serial' parameter, leaving device selection entirely undocumented. This is a significant gap for a 2-parameter tool.

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 and resource: 'Type a string into the focused field.' This clearly distinguishes it from sibling tools like keyevent (which sends key presses) and run_shell (which executes commands). An agent can tell what it does without opening the schema.

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 explicit when-to-use or when-not-to-use guidance is provided. It implies a focused field must exist but does not say to use tap or other focus tools first, nor does it mention any alternatives or prerequisites. The agent must infer usage context entirely.

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