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

With no annotations, the description carries the full burden; it does disclose a display precondition and an empirically failing method, which is genuinely useful behavioral context. It omits what happens when there is no back history, whether it blocks until the page transition completes, and how it interacts with the timing parameters.

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?

Two sentences, zero filler: the primary action and its precondition come first, then the method caveat. The parenthetical recovery steps are actionable rather than padding.

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 six-parameter, annotation-free navigation tool with no output schema, the description covers the critical precondition and one method caveat but leaves the whole timing/settling family (ms, timeout, stable_for, wait_change) undocumented, forcing the agent to guess defaults and blocking behavior.

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 17% — only 'settle' is documented in the schema. The description adds real meaning for one parameter by explaining that method=swipe uses the left-edge gesture and did not navigate in testing, but ms, timeout, stable_for, and wait_change remain unexplained in both schema and description.

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?

States a specific verb and target (taps the toolbar back arrow in Safari), so the agent knows exactly which control is actuated. It implicitly separates itself from generic tap/swipe siblings, but never names them, so the differentiation is inferred rather than explicit.

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?

Gives a concrete precondition (toolbar must be showing) and two recovery actions (scroll up a little, or tap the bottom bar first). It also warns that the swipe alternative did not navigate in testing, effectively steering the agent to method=button. No other sibling alternatives are named.

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