safari_element_exists

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

With no annotations, the description carries the full burden of disclosing behavior. It implies a read-only check, but it does not explicitly state the return value, whether the tool waits for the element, what happens when no element matches, or how invalid selectors are handled. This is a significant gap, especially alongside safari_wait_for.

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 one concise sentence with the verb and subject front-loaded and no filler. It earns its place as a clear purpose statement, though its brevity does contribute to missing behavioral and parameter 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 no annotations, no output schema, and no parameter descriptions, the description alone should be complete enough for an agent to call the tool correctly. It is not: return type, tab/window semantics, waiting behavior, and relation to safari_wait_for are all absent. It is a clear but under-specified definition.

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 description coverage is 0%, so the description must compensate. It does clarify that 'selector' is a CSS selector, but it leaves 'tab' and 'window' semantically undefined: there is no explanation of what the integers refer to, what null/default means, or how the two interact. That is a meaningful gap for a 3-parameter tool.

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 action ('Check whether') and the resource ('a CSS selector matches any element in a Safari tab'), making the boolean-existence purpose obvious. It does not explicitly call out how it differs from siblings like safari_wait_for, but the core function is recognizable enough to avoid confusion at a high level.

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?

There is no guidance on when to use this tool versus alternatives. It never mentions that safari_wait_for is the appropriate choice when an element may need time to appear, nor that safari_element_exists is a non-waiting preflight check. The agent is left to infer usage context from the tool name alone.

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