ACTION_SET_ALARM

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

With no annotations, the description carries the full burden and does well: it discloses that the alarm is created by firing an Intent at the system clock app rather than silently, that background launch restrictions can cause the screen not to appear, and that the outcome surfaces as alarm_success / alarm_error variables. It omits permission prerequisites and whether the user must confirm the alarm manually.

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?

Front-loaded with the purpose, then explicitly separated into input mechanism, output variables and caveats, so an agent can scan it quickly. Minor waste: a duplicated period ('。。') and a run-on final clause about interpolation and variable snapshots.

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 6-parameter, annotation-free tool with no output schema, the description covers the essential gaps: it names the two output variables and explains the non-silent Intent mechanism and its failure mode. The generic workflow controls (require, on_error, node_timeout_ms) are left entirely to the schema, which is acceptable at full coverage but leaves nothing in prose about how a failed alarm interacts with on_error.

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 the schema already documents hour, minute, label, require, on_error and node_timeout_ms in detail. The description's only added semantics are ${var} interpolation for string parameters — which the schema already states for label — and the variable-snapshot return format. Baseline 3 applies.

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 concrete verb and resource ('设闹钟' – set an alarm) and specifies the mechanism and payload: opens the system clock app's new-alarm screen with hour, minute and label. No sibling tool covers alarms, so there is no ambiguity to resolve, and an agent knows exactly what will happen without opening the schema.

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 implies the operating context (must be able to launch the system clock UI) and warns that background launch restrictions may prevent the dialog from appearing, which helps an agent judge feasibility. It does not, however, name any alternative (e.g. ACTION_WAIT_UNTIL_TIME for a purely scheduled wait) or state when an agent should prefer a different approach.

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