press_key

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

With no annotations provided, the description carries the full burden of behavioral disclosure. It mentions the action ('press a key') and a return value, but fails to describe critical behaviors: whether this requires device interaction permissions, if it's synchronous/asynchronous, potential side effects (e.g., app navigation), or error conditions beyond a generic message. This is inadequate for a mutation tool with zero annotation coverage.

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?

The description is well-structured and front-loaded with the core purpose, followed by clear sections for arguments and returns. It avoids unnecessary fluff, though the example key codes could be more comprehensive to enhance clarity without sacrificing brevity.

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?

Given the tool's moderate complexity (a single parameter mutation), no annotations, and an output schema that only specifies a string return, the description is minimally adequate. It covers the basic action and parameter meaning but lacks depth on behavioral nuances, error handling, and integration with sibling tools, which would be needed for robust agent use.

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 adds significant value beyond the input schema, which has 0% description coverage. It explains that 'key_code' is an integer representing specific keys (e.g., 3 for HOME, 4 for BACK), providing essential context that the schema lacks. However, it doesn't list all possible key codes or reference a documentation source, leaving some ambiguity.

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?

The description clearly states the verb ('press') and resource ('a key on the device'), making the purpose immediately understandable. However, it doesn't explicitly differentiate from sibling tools like 'press' (which might be similar) or other input-related tools, keeping it from a perfect score.

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 provides no guidance on when to use this tool versus alternatives like 'input_text', 'click', or 'press'. It lacks context about typical use cases (e.g., navigation vs. text input) or prerequisites, leaving the agent to infer usage from the tool name alone.

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