screenshot

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

With no annotations, the description carries the full burden of behavioral disclosure. It reveals the output format (PNG file path), the active-tab vs. URL behavior, the element-only behavior of `selector`, and the overlay behavior of `som`. It does not mention all side effects, but for a screenshot tool the disclosed behavior is reasonably complete.

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 dense but well-structured: it front-loads the purpose, then explains the key parameter modes, then states the return value. Every sentence earns its place, and there is no redundant 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 tool with 4 optional parameters, no annotations, and no schema descriptions, the description covers most behaviors but still omits `full_page` and does not clarify how `url`, `selector`, and `full_page` interact. An output format/path is mentioned, and an output schema exists, which helps, but the combination of these gaps makes the tool not fully self-sufficient.

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 4 parameters and 0% schema descriptions, so the description must compensate. It adds meaning for `url`, `selector`, and `som`, but it says nothing about `full_page` even though this parameter defaults to `true` and could significantly change the capture area. This leaves a meaningful semantics gap.

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: producing a PNG screenshot of either the active session tab or a page identified by URL, with optional element-level and Set-of-Mark behavior. This is specific and understandable, but it does not explicitly distinguish it from siblings such as `snapshot` or other browser-capture tools.

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 useful context: omit `url` to capture the active session tab, use `selector` for an element-only screenshot, and set `som=true` for labeled interactive elements. However, it never says when this tool should be chosen over alternatives like `snapshot` or when it should be avoided, so the guidance is implied rather than explicit.

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