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

With no annotations, the description carries the full burden, and it does disclose two important traits: typing overwrites existing content, and the tool returns the new screen. It omits error behavior for invalid/stale refs and any focus or timing preconditions, which matter for an unattended UI-driving tool.

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 with the operation and its overwrite side effect front-loaded, followed by the return value. 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?

The tool is simple (4 params, no output schema), and the description covers the return value and the destructive-ish overwrite behavior. Still missing are preconditions (field focus, valid ref) and failure behavior, which an agent needs before driving a UI blindly.

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 75%: ref, enter, and session are documented in the schema, but text has no description. The description adds meaning for text via "replaces its content" (overwrite rather than append), but does not clarify literal-typing semantics such as newlines or special characters.

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 into a text field by ref") and clarifies the effect ("replaces its content"), which separates it from sibling mutators like tap or scroll. It does not explicitly name an alternative tool or contrast with them, 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?

Usage is only implied: the "by ref" phrasing hints that the ref comes from a prior screen inspection, but there is no explicit statement of when to use this versus tap/scroll or whether the field must be focused first. No exclusions or prerequisites are given.

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