Type text

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

Annotations already declare a non-readonly, non-destructive write. The description adds significant behavioral detail beyond that: spaces are encoded as %s, shell metacharacters are quoted, and a literal '%s' still becomes a space on the device. It also states the focus prerequisite and suggests verification.

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 front-loads the core action, then adds encoding caveats, then prerequisites/verification. Every sentence earns its place, with no wasted phrasing.

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 write tool with full schema coverage, annotations, and no output schema, the description covers the essential context: what it does, how to prepare (focus), how to verify (screenshot), and encoding pitfalls. Device selection is delegated appropriately to the 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 coverage is 100%, so the baseline would be 3. The description adds meaningful value for the `text` parameter by explaining encoding rules and the %s caveat, though it says nothing additional about the `device` parameter beyond the schema.

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 ('Type text') and target ('focused input field'), and even gives the underlying adb command. It clearly distinguishes itself from siblings like tap, key_event, and shell by focusing on text entry into an already-focused field.

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?

Provides a clear prerequisite ('Focus the field first (tap it)') and a verification step ('screenshot to confirm what was typed'). It does not name explicit alternatives such as key_event for special keys or shell for arbitrary input, so it falls short of full when/when-not guidance.

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