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

With no annotations provided, the description carries the full burden of behavioral disclosure. It fully discloses polling behavior, substring matching scope, return shape, the non-error semantics of found=false, the visibility limitation, and the requirement for an active iOS session. This is comprehensive and exceeds what annotations would typically provide.

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 information-dense but every sentence adds value. It front-loads the core purpose, then sequentially covers matching, return shape, error semantics, visibility caveat, and prerequisites. No redundancy or fluff; structure guides the reader from high-level intent to operational detail.

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 and lack of an output schema, the description covers everything an agent needs: what it does, how matching works, return shape, error handling, visibility caveat, and session requirement. It is complete for safe and correct invocation.

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?

The schema covers 100% of parameters, so baseline is 3. The description adds meaningful context beyond the schema: it explains that label is matched as a case-insensitive substring across multiple fields, and clarifies the meaning of the returned found flag. However, it does not add detail for timeout and interval beyond what the schema already provides, so it doesn't fully merit a 5.

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 states a specific verb and resource ('Wait until an element appears on screen') and clearly distinguishes itself from its sibling device_wait_for_element by naming it as the counterpart. It also clarifies the matching semantics (case-insensitive substring against label/name/value/placeholder), making the tool's purpose unambiguous.

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?

It explicitly names the alternative (device_wait_for_element) and implies when to use this iOS-specific variant. It provides crucial usage guidance: found=false is a normal assertion result, not an error, and warns that a hit does not prove visibility, directing the user to check element.visible. This tells the agent exactly when and how to use the tool correctly.

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