glass_screenshot

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

Beyond the readOnlyHint annotation, the description discloses important behaviors: captures are clipped at display edges, the returned width/height reflect the actual captured size, a smaller frame indicates clipping, and only a fully off-screen surface errors. It also clarifies the screenshot's evidential limitation.

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 front-loaded with the core purpose, then gives usage routing, then covers edge-case behavior. Every sentence earns its place, and there is no filler or repetition of schema boilerplate.

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?

Coverage is strong for an invoke-time decision: purpose, alternatives, clipping, and error conditions are all present. However, there is no output schema, and the description only mentions returned width/height without stating how the screenshot image itself is returned, which is a minor completeness gap.

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?

Schema description coverage is 100% and the schema already explains window_id and region semantics in detail, including window-relative coordinates and optionality. The description mostly restates 'window-relative region' without adding substantial parameter-level meaning beyond the schema.

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 states a specific verb and resource: 'Capture current visual evidence from the app window' as a 'lossless WebP screenshot.' It also distinguishes itself from sibling wait tools by explicitly saying it proves pixel visibility, not semantic state or transition completion.

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 gives explicit when-to-use guidance and names specific alternatives: use glass_wait_for_element for accessible conditions, glass_wait_for_region for pixel transition completion, and glass_wait_stable for visual quiescence. This lets an agent route correctly without guessing.

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