Desktop: Screenshot

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

With no output schema, the description usefully discloses the return payload (cursor position, window list, PNG image) and the permission requirement, which the annotations do not cover. It does not address the surprising destructiveHint=true / readOnlyHint=false annotations, leaving an agent to wonder why a screenshot is flagged as a destructive write; that gap keeps it below 5.

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?

Four short sentences, each carrying distinct information: identity/scope, return payload, sibling routing, and precondition. Front-loaded with the differentiator and free of filler.

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 zero-required-param, single-parameter tool with no output schema, the description covers what it returns, what it deliberately omits, when to prefer the sibling, and the auth prerequisite. Nothing an agent needs to invoke it correctly is missing.

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 single 'display' parameter is fully documented in the schema, so the baseline of 3 applies. The description adds nothing about display indices, but it does not need 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?

States a specific verb and resource ('Fast screenshot-only desktop snapshot') and immediately differentiates itself from its closest sibling by noting it 'Skips UI element extraction.' An agent can distinguish it from desktop_snapshot and cdp_screenshot without opening any schema.

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?

Explicitly names the alternative and the condition that selects it: 'Use desktop_snapshot when you need interactive element coordinates.' It also states the precondition ('Requires desktop_permission in the active mission step'), so both routing and eligibility are covered.

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