get_safe_area_insets

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

With no annotations, the description carries full burden. It clearly indicates this is a read operation and specifies what it reads (insets and stylesheet check). It does not mention side effects, but none are expected. No contradictions.

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 three sentences, front-loaded with the main action. Every sentence adds information without redundancy or fluff. Highly efficient.

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 no parameters and no output schema, the description adequately covers the tool's purpose and behavior. It explains what values are returned and under what conditions they are non-zero. A slight gap is the lack of explicit return format, but it is not critical.

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 tool has no parameters and schema coverage is 100%, so baseline is 3. However, the description adds value by detailing the output (top, right, bottom, left insets) and the additional check on stylesheets, providing more context than the empty schema alone.

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 reads CSS safe-area-inset values and checks for usage of the env() function in stylesheets. It is specific about the resource (safe-area-inset values) and verb (Read). It naturally distinguishes from sibling tools, as no other tool explicitly does this.

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 provides context (non-zero on notched iPhone with viewport-fit=cover) but does not explicitly state when to use this tool over alternatives or when not to use it. Lacks explicit when-to-use/when-not-to-use guidance.

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