browser_take_screenshot

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

Annotations already mark this as read-only and non-destructive. The description adds an important behavioral limitation: the screenshot cannot be used as a basis for actions, which is not captured in annotations. However, it doesn't describe how the screenshot is returned or any side effects beyond the annotation hints.

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?

Two concise sentences: the first states the purpose, the second provides a crucial usage caveat. No redundant words, and the structure effectively front-loads the core action before delivering the warning.

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?

While the schema covers parameters thoroughly, the description omits what the tool returns (e.g., file path, image data) after taking the screenshot. The note about not using it for actions suggests the image is for visual inspection, but this isn't explicit. For a tool with no output schema, this is a notable 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?

All 6 parameters are fully documented in the schema with detailed descriptions (e.g., scale explains CSS vs device pixels, fullPage notes it cannot be combined with element). The description itself adds no parameter-level detail, so it aligns with the schema-heavy baseline of 3.

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 'Take a screenshot of the current page' with a specific verb and resource. It distinguishes itself from browser_snapshot by explicitly noting 'use browser_snapshot for actions,' clarifying that this tool is for visual capture while the alternative is for actions.

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 warns 'You can't perform actions based on the screenshot, use browser_snapshot for actions,' providing a clear exclusion and naming the alternative. This gives the agent concrete guidance on when not to use this tool and which sibling to use instead.

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