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

Annotations already declare readOnlyHint=true, openWorldHint=false and destructiveHint=false, so the safety profile is covered. The description adds genuinely useful behavior beyond that: the capture defaults to the latest draft unless live is set, and it reflects what visitors see. It does not discuss latency or capture limits, but for a read-only tool this is solid.

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?

Three sentences, each carrying a distinct point (purpose, return value, default behavior), with the primary intent front-loaded. Slightly conversational phrasing but no wasted sentences.

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?

An output schema exists, so return-format details are unnecessary here. The description covers the tool's scope, the visitor-view semantics, and the draft/live default; nothing an agent needs to invoke it correctly is missing, though alternative-tool routing is left out.

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 coverage is 80%, so the schema already documents live, path, device and full_page. The description's 'Shows the latest draft unless live is set' largely restates the live parameter's schema description, and 'computer or a phone' echoes the device enum. It adds framing but no new parameter-level detail, so the baseline 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?

States a specific verb ('look at' / capture a screenshot) and resource (one of the user's WebTwizz sites), and frames the outcome ('a picture of a page as visitors see it'). It is distinguishable from siblings like show-preview or get-site, which do not return a rendered visitor-view image.

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?

Gives concrete when-to-use scenarios: check a change, review the design, compare against the user's request. However, it names no alternative tool or explicit when-not condition, so an agent must still infer when screenshot-site beats show-preview.

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