Type text

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

With no annotations, the description carries the full burden and does it well: it explains the mechanism of each `via` mode, gives a timing figure (~1ms), states that verify defaults to true and fails loudly, and warns about positional keycodes being rewritten by non-ASCII host layouts. It omits the behavior of `submit` and `device`, which are behavioral as well as structural.

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?

Front-loaded with the action, then field targeting, then strategy selection, then verification — a sensible order with no filler. The em-dash clauses are dense but each carries real information; the sentence on keyboard layouts is long but earns its place as a warning.

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 6-parameter tool with a nested targeting object, no output schema and no annotations, the description covers the hard parts (targeting ambiguity, mode choice, verification). The gap is `submit` and `device`, which an agent would have to infer from the bare 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 0%, so the description must compensate. It meaningfully documents `into` (matching by testID, placeholder, accessibilityLabel), `via` with defaults, and `verify` with its default and failure mode, but `text`, `device` and `submit` are entirely unaddressed. It also refers to `accessibilityLabel` while the schema field is named `label`, creating a naming mismatch an agent must resolve.

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?

Opens with a specific verb and resource: 'Type text into a text input.' An agent can immediately separate this from tap, press_key or eval_js. It does not explicitly name a sibling to contrast with, 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?

Gives concrete selection conditions: omit `into` only when a single input is on screen, and pick `js`/`os`/`auto` based on the tradeoff described. It lacks any guidance on when typing is not appropriate (e.g. use press_key for special keys) or ordering relative to tap/observe.

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