Type text

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

With no annotations, the description carries the full burden; it does disclose the ASCII-only limitation and that newlines press Enter, which are real behavioral traits. It omits failure modes, whether the app must be foregrounded, timing/retry behavior, and whether typed text replaces or appends by default.

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 tight sentences, front-loaded with the primary action, then the targeting variant, then behavioral caveats. Nothing is redundant or padded.

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 input tool with no annotations and no output schema, the description covers action, targeting, and the two most surprising constraints (ASCII-only, newline=Enter). A brief note on what happens when no field is focused or on failure would close the remaining gap.

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 baseline is 3, but the description adds genuine semantics: ref vs field as alternative targeting mechanisms, and that embedded newlines in text act as Enter presses. clear, submit and serial are left to the schema, which documents them adequately.

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) and target (focused field) plus the optional pre-step of tapping a field by ref or visible text. This implicitly separates it from phone_tap and phone_key, though it never names a sibling explicitly.

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?

Explains both invocation modes: type into whatever is already focused, or target a field via ref (index) or field (visible text/hint). No explicit when-not guidance or named alternatives, but the context needed to choose a path is present.

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