Preview A2UI

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

Annotations already mark the operation read-only, idempotent, and world-opening. The description adds the key behavioral trait that the preview auto-updates with changes from sibling tools, and that it returns a shareable/manually-openable URL. No contradictions with annotations.

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 short sentences, each providing distinct information: what it opens, auto-update behavior, and return value. No redundant or filler content.

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?

For a zero-required-parameter read-only tool with no output schema, the description covers the operation, update behavior, and return value. Annotations cover the safety profile, so nothing essential is missing.

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 single parameter open_browser is fully documented in the schema (100% coverage). The description adds context around its purpose by mentioning the URL can be shared or opened manually, implying why one would set open_browser to false. This is incremental value beyond the schema, so slightly above the high-coverage baseline.

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 names a specific action and subject: 'Open a live preview of all A2UI surfaces in the browser.' This clearly differentiates the tool from siblings that get state, create/update surfaces, clear, or poll events. No ambiguity about what it does.

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 indicates a clear context: it is a preview that auto-updates when changes are made using other a2ui_* tools, so an agent can use it to observe the effects of prior mutations. However, it does not explicitly state when to prefer preview over a2ui_get_state or when not to use it, so it stops short of full exclusion guidance.

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