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

Annotations only say readOnlyHint=false and destructiveHint=false; the description adds real value beyond that with the boot-screen sequence, the cold-start semantics, the fact that storage survives, the return value ('first screen'), and the device_log side effect tagged as simulated. It stops short of stating how long the restart takes or whether a session/credential state is invalidated.

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?

Four compact clauses, front-loaded with the action and the mechanism, then the distinguishing behavior, the return, and the logging side effect. Nothing is redundant and no sentence fails to earn its place.

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 one-parameter tool with annotations and no output schema, the description covers action, persistence semantics, return value, and logging. Missing only preconditions such as whether the device must be unlocked or whether the session remains valid after a cold start.

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?

There is a single parameter and schema description coverage is 100%, with the schema already explaining it as 'Session from open_app'. The description adds nothing about the session argument, so the baseline of 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 specific verb and resource ('Restart the simulated phone') plus the mechanism ('from the power menu') and outcome ('app starts fresh (cold start)'). The phrase 'Storage is kept' implicitly carves it out from device_reset, but no sibling is named explicitly, so differentiation is inferred rather than stated.

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 'cold start, storage kept' framing hints at when this is preferable to device_reset or kill_app, but there is no explicit when-to-use, when-not-to-use, or named alternative. The agent must infer the choice from sibling names alone.

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