preview

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

Annotations already declare readOnlyHint=true, so safety is covered. The description adds one genuinely useful behavioral note beyond that: the returned URL only works while the server is running, which tells an agent the result is ephemeral. It does not say whether the preview must be started, what it shows, or whether multiple previews can coexist.

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 short sentences with no filler, and the core information (local URL, browser, server lifetime) is front-loaded. It is efficient, though brevity here comes at the cost of specification rather than being purely a virtue.

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?

With one required undocumented parameter, no output schema, and a preview-oriented purpose, the description should say what the URL points at and how long it remains valid in concrete terms. It covers the lifetime caveat, which is the most important thing, but leaves the parameter and the invocation flow unaddressed.

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% for the single required 'project' parameter, so the description carries the full burden and explains nothing about it — no format, no identifier source, no example. "The page" hints at a project but never links it to the required argument.

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 is phrased as a noun ("A local URL that plays the page live in a browser") rather than stating an action, so it describes the output more than the operation. It does convey the resource domain (a live browser preview) but gives no verb and does not distinguish it from siblings such as render, stills, or render_status.

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?

There is no guidance on when to call this versus render, stills, or render_status, and no prerequisites or exclusions. The only conditional information is an environmental one (the URL lives as long as the server runs), not a usage rule.

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