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

Goes well beyond the annotations, which only declare this is not read-only/idempotent/open-world. It discloses refusal semantics with a rationale, the force bypass, the direct-input path that skips the focused-field check, and the requirement of an active iOS automation session.

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?

Front-loads the core action and the focus precondition, and nearly every clause carries information. The aside explaining the previous buggy behaviour ('the old behaviour still said it was typed') is longer than needed to justify the refusal, costing a little tightness.

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?

With no output schema and only three documented parameters, the description supplies everything an agent needs: the session precondition, the focus precondition, the refusal/force path, and the direct-input exception. Nothing material is left unstated.

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 the baseline is 3, but the description adds real meaning: force:true is scoped to 'surfaces where the active element is not reported' and framed as rare, and the \n-as-Return behaviour is restated with a concrete example ('user@example.com\n' to submit).

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?

Names a specific verb+resource+target: typing text into the FOCUSED field on an iOS device. It implicitly separates itself from raw-input siblings such as ios_key_hid and from generic typing tools by stating the focus precondition up front.

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?

Explicit when-to-use (tap a text field first), an explicit failure mode and why it exists (refuses when nothing is focused rather than falsely reporting success), the escape hatch (force:true, flagged as rare), and the direct-input-only exception with the note that the check is skipped there.

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