press_key

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

No annotations are present, so the description carries the full behavioral burden. It only names the action and valid keys; it does not disclose that keys like power, home, back, or volume can change device state, trigger navigation, or produce side effects. It also says nothing about return behavior or failure modes.

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 one-sentence definition is followed by a compact, scannable list of allowed keys. No filler words, and the verb and resource are front-loaded before the enumeration.

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 single-parameter action tool with an output schema, the description is nearly complete: the agent knows the operation and all valid inputs. It falls short of 5 only because it omits behavioral context and alternative routing, but nothing essential is missing for making the call.

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?

The description fully enumerates all valid values for the key parameter, which is the core semantic content; the schema merely references that list. This adds real meaning beyond the schema, even though schema coverage is marked as 100%.

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 ('Press') and a well-defined resource category ('navigation, hardware, or system key'), then enumerates the exact allowed keys. This makes it distinguishable from siblings like tap and type_text, though it does not explicitly contrast itself with them.

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?

No guidance is given about when to use press_key instead of alternatives such as tap, type_text, scroll, or swipe. The key list implies some usage context, but there are no explicit conditions, exclusions, or comparisons to sibling tools.

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