screenshot

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

With no annotations provided, the description must fully disclose behavioral traits. It only says 'capture a screenshot', which implies a safe read operation but does not mention side effects, output format, or requirements. This is minimal and leaves most behavioral information to be inferred from the schema or learned externally.

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 only two sentences and gets straight to the point, with no redundant language. It is appropriately short for a simple utility, though it sacrifices important details for brevity. It does not directly repeat schema information, earning 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?

Given the tool has 32 parameters, no output schema, and no annotations, the description is too thin. It fails to explain return values, which parameters are essential for common scenarios, or any default behaviors. The high schema coverage helps but does not substitute for missing high-level context like 'what happens if no path is specified'.

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 84% coverage, so the baseline is 3. The description adds a small grouping by mentioning 'scope, density, size, or annotations', which loosely corresponds to parameters like 'surface', 'scale', 'pixelDensity', and 'overlayRefs'. This adds minimal value beyond the schema descriptions but does not introduce confusion.

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 primary action: 'Capture a screenshot of the active app or web session.' It uses a specific verb and resource, which immediately conveys the tool's purpose. However, it does not differentiate from the sibling tool 'snapshot', which could be similar, so it misses the top 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?

There is no guidance on when to use this tool vs. alternatives. The phrase 'when needed' implies situational use but gives no concrete context, exclusions, or comparisons to siblings like 'snapshot' or 'record'. This leaves the agent without clear selection criteria.

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