screenshot

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

With no annotations, the description carries the behavioral disclosure burden. It transparently explains PNG format, active-tab vs URL modes, selector behavior, Set-of-Mark output with numbered red frames, and the returned file path. The only notable omission is full_page behavior, but that is more of a parameter-semantics gap than a behavioral surprise.

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 compact, front-loaded with the core behavior, and uses explicit WHEN/NOT WHEN sections. Every sentence adds operational value and there is no 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?

The description covers purpose, usage boundaries, return value, and most parameters, which is solid for a moderately complex tool. However, one of four parameters, full_page, is entirely absent, and its default true could meaningfully affect the screenshot result. Given the 0% schema coverage and no annotations, this is a real 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 0%, so the description must add meaning. It does explain som, url, and selector in practical terms, but full_page is not mentioned at all despite having a default of true and no schema description. This leaves one important parameter semantically undocumented.

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 action and resource: it captures a PNG screenshot of either the active session tab or a page by URL, and optionally only a selected element. It also differentiates itself from snapshot/fetch_page for text-only needs, so an agent can distinguish it from siblings.

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?

Usage is explicitly gated with КОГДА (visual checks: layout, canvas, captcha, images) and НЕ КОГДА (texts/links only), naming snapshot/fetch_page as cheaper alternatives. This gives clear when-to-use and when-not-to-use guidance.

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