Take screenshot

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

With no annotations, the description carries the full burden. It discloses key behaviors: viewport-only capture (not full page), saving as <actionId>.png in the session log directory, and returning file path plus scroll position and viewport. This is substantial, though it omits details like error handling or whether the operation is synchronous.

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 two sentences with no redundancy. The core action is front-loaded, and the details on saving and return are concise and relevant.

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 no output schema, the description adequately explains the return value (file path, scroll position, viewport) and the file location. It could mention potential failure modes or how to access the file, but for a simple tool with one parameter, it is reasonably complete.

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 covers the only parameter (sessionId) with a clear description, so schema coverage is 100%. The tool description adds no additional parameter meaning, so the baseline of 3 applies.

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 a specific verb ('captures') and resource ('current viewport of the session page'), and explicitly distinguishes from full-page capture. It also details the output (saved .png, file path, scroll position, viewport), which differentiates it from sibling tools like get_page_snapshot or get_viewport_size.

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 implies usage for visual capture but does not explicitly say when to use this tool versus alternatives like get_page_snapshot or get_viewport_size. There are no conditions, exclusions, or references to sibling tools, leaving usage guidance to inference.

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