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

Goes well beyond the annotations by disclosing that the build is asynchronous, that it consumes credits from the authenticated account, and that the immediate response is a buildId rather than a finished app. Those are the operational facts an agent most needs for a non-idempotent, open-world, credit-spending call.

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 sentences with zero filler: the action and cost/async contract come first, the next-step pointer second. Every clause carries actionable information.

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?

Despite having no output schema, the description states what is returned (buildId) and how to get the eventual result (poll get_build_status), so an agent can complete the full loop. Nothing material is missing given that annotations carry the safety profile and the schema carries parameter detail.

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 mode, framework, prompt, and _confirmed are already documented inline, including enum values and defaults. The description adds no additional parameter meaning, so 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?

Specific verb+resource with product context ('Build a working web app ... with PromptUI') and an explicit boundary against the sibling deploy_app by framing this as the build step. It also names the return value (buildId), so an agent can distinguish it from list_builds/get_build_status without opening schemas.

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?

Explicitly routes follow-up to get_build_status for progress and the preview link, which is the key orchestration guidance. It lacks an explicit 'when not to use / use deploy_app instead' exclusion, which is the only missing piece.

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