Type Text

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

Annotations already declare readOnlyHint=false, destructiveHint=false and openWorldHint=true, so the safety profile is covered. The phrase 'into the focused element' adds a real behavioral constraint — the tool silently depends on prior focus state — but nothing is said about failure behavior when no element is focused or about the submit side effect.

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?

A single front-loaded sentence with no filler, which is appropriate for a simple action. It is arguably too terse for the prerequisites involved, but there is no bloat to trim.

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 tool is simple and the schema carries all three parameters, so the definition is minimally viable. It still omits the focus prerequisite, what happens when nothing is focused, and any indication of what is returned, leaving gaps for a tool that mutates device state.

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 100%: text, device (with a pointer to mobile_list_available_devices) and submit are all documented in the schema, including the default for submit. The description adds no syntax, formatting, or encoding detail beyond that, so the baseline 3 applies.

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 and target: type text into the focused element. That is clearly distinct from sibling tools like mobile_press_button or mobile_click_on_screen_at_coordinates in effect, but the description never names those siblings or explicitly contrasts the interaction modes.

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 when-to-use guidance, no stated prerequisites (e.g. that a field must already be focused/clicked first), and no routing to alternatives such as mobile_press_button for key events. The agent must infer the calling context entirely.

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