ACTION_GLOBAL_NAV

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 the accessibility requirement, the output variables (nav_success, nav_error), ${var} interpolation, and that results come back as a variable-snapshot JSON — useful context beyond the schema. However it omits risk profile for disruptive actions (power_dialog, lock_screen) and any failure/timeout behavior for the navigation itself.

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?

A single dense paragraph that front-loads the action list, then the prerequisite, then output and interpolation semantics. No filler, though the output-variable note could be separated for scannability.

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 four-parameter action dispatcher with no output schema, the description names the result fields (nav_success, nav_error), states the prerequisite, and explains interpolation. It lacks only risk/lifecycle detail for the more disruptive actions.

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 100%, so action, require, on_error, and node_timeout_ms are already documented in the schema. The description adds only the ${var} interpolation note, which lightly relates to string parameters like 'require', but explains nothing about the workflow-control parameters.

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+resource (accessibility global actions) and enumerates the eight operations (back, home, recents, notifications, quick settings, power menu, lock, screenshot), matching the enum in the schema. It hints at differentiation via '（需无障碍）' against siblings like ACTION_SCREENSHOT or ACTION_GLOBAL_KEY, but never names them explicitly.

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 conveys the prerequisite (accessibility service required, no Shizuku) and implied usage — pick one of these eight global navigation actions. There is no explicit when-to-use versus ACTION_GLOBAL_KEY or ACTION_SCREENSHOT, and no guidance on which actions are destructive (power menu, lock screen).

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