Type Text

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

Annotations indicate readOnlyHint=false (write operation), openWorldHint=true, and destructiveHint=false. The description adds that ambiguous or stale targets are rejected, which is useful behavioral context. However, it doesn't disclose side effects like what happens to existing text or whether it overwrites, or the exact behavior of the 'submit' flag beyond the schema. Given annotations cover the write nature, the description adds moderate value.

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 is concise (two sentences) and front-loads the primary purpose. The second sentence adds the optional focusing behavior and rejection criteria, which is important for correct usage. No excessive detail or fluff; 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?

Given the tool's moderate complexity (5 parameters, nested target object, no output schema), the description covers the core behavior and the key constraint about target rejection. However, it could benefit from explaining the difference between 'ref' and 'target' and when to use each, especially since both are optional. With no output schema, return value description is not required, but usage nuances are missing, making it slightly incomplete but close to full.

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%, meaning all parameters have descriptions in the schema. The description adds the context that targets must be exact and that ambiguous/stale ones are rejected, which enhances understanding of the 'target' and 'ref' parameters. However, it doesn't provide deeper semantics like formatting requirements for 'text' or the relationship between ref and target, so it adds some value beyond 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?

The description clearly states the specific action ('Type text into the focused element') and the resource (the focused element). It also mentions the optional ability to provide a ref or target to focus first, which distinguishes it from other input-related tools like clicking or pressing buttons. This clearly differentiates it from siblings like mobile_click_on_screen_at_coordinates and mobile_press_button.

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?

The description gives clear context on when to use the tool (type text into focused element) and optionally mentions providing a ref or target to focus. However, it doesn't explicitly state when NOT to use it or mention alternatives, such as using mobile_click_on_screen_at_coordinates for tapping or mobile_press_button for button presses. The guidance is clear but lacks explicit exclusions.

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