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

With no annotations provided, the description carries full burden and does excellent work: it discloses that the tool refuses when nothing is focused (unlike old behavior that falsely reported success), explains why (WDA accepts keystrokes regardless), and warns that without a focused field text goes nowhere. Force:true is documented as rare. All behavioral quirks are transparent.

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 front-loaded with the core action, uses efficient single sentences, and provides just enough technical detail. Slightly above 3 because it packs significant behavioral nuance into a compact paragraph without fluff. Could be slightly more concise on the refusal behavior.

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 3-param tool with 100% schema coverage and no output schema, the description is very complete: covers prerequisites, edge cases, behavioral traits, and all parameters. No mention of return value (e.g., whether it returns success/failure), but output schema is absent which reduces burden. Slight gap: doesn't explicitly state the tool returns nothing meaningful or may throw error on refusal.

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. The description adds value beyond schema by explaining the newline escape in context of Return/Go and providing a concrete example. It also clarifies force:true is for rare cases where active element is not reported. Minor deduction: example usage could be more general.

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 tool types text into the focused field on an iOS device, distinguishing it from sibling tools like session_send_keys or web_type which are for web or other contexts.

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 explicitly states the prerequisite ('tap a text field first'), explains how to use newline for Return/Go (with example), and notes when force:true is needed ('for surfaces where the active element is not reported'). It also explains the edge case of no focused field.

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