screenshot_annotated

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

With no annotations, the description carries the burden of disclosure. It explains the overlay behavior, the connection to get_elements(), and the base64-encoded PNG output. However, it does not mention potential prerequisites (e.g., accessibility permissions) or failure modes, but for a screenshot tool this is adequate.

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 three concise sentences, each adding meaningful information: action, element-index correspondence, usage guidance, and return format. There is no redundant or vague wording, making it highly efficient.

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?

With only one parameter and an output schema, the description covers the core functionality, usage, and output format. The missing explanation of 'device' is a notable gap, but overall the tool is simple enough that the description is largely complete.

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 input schema has one required parameter 'device' with zero description, and the description does not clarify its meaning or possible values. Since schema coverage is 0%, the description should have compensated, but it does not, leaving the agent uncertain about what 'device' refers to.

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 tool's function: 'Take a screenshot with numbered element labels overlaid on interactive elements.' It also distinguishes itself from sibling tools like 'screenshot' by explaining the labels correspond to get_elements() indices, making it unique and well-scoped.

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 a clear use case: 'Use this when you want to SEE the screen with elements visually labelled.' It indicates when to use the tool, though it does not explicitly mention alternatives or exclusions, which would warrant a 5.

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