Create A2UI Surface

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

Annotations indicate this is a mutating, idempotent, non-destructive operation. The description adds useful context beyond that: it explains what a surface is, reinforces the prerequisite relationship, and documents the return value as a JSON confirmation. This matches the annotation profile with no contradictions.

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 well-organized with a definition, prerequisite note, args, return info, and example. It is not excessively long, but some of the Args section duplicates the schema, slightly reducing information density.

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 two-parameter tool with full schema coverage and no output schema, the description is complete: it states the purpose, the prerequisite, the parameters, the response, and gives a realistic example. An agent has everything needed to call it correctly.

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 100%, so the schema already documents both parameters fully. The description restates the parameters and gives an example, which adds minor convenience but no new semantic meaning beyond what the schema provides.

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?

Description states a specific verb ('Create'), a concrete resource ('A2UI surface'), and its role as a UI container. It clearly distinguishes the tool from siblings like a2ui_update_components and a2ui_get_state by establishing the surface as the prerequisite top-level container.

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 explicitly says 'You must create a surface before adding components to it,' which gives clear sequencing guidance. It does not explicitly name alternatives or exclusion cases, but the context makes it obvious when this tool should be used first.

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