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

Annotations already declare readOnlyHint=true and idempotentHint=true, so the description doesn't need to restate safety. It adds meaningful behavioral detail by listing the possible outcomes (building, needs_clarification, completed with previewUrl, failed), which goes beyond the annotations and tells the agent what to expect from the 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?

The entire description is one focused sentence that front-loads the action and resource, then efficiently lists the return states. Every part contributes to agent understanding with no filler or repetition of schema details.

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?

This is a low-complexity tool with a single documented parameter and only four possible outcomes, all of which the description names. Since there is no output schema, listing the statuses is essential and is done well. Minor gaps remain around error cases like an unknown buildId, but they are not critical for a simple status checker.

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 100%, and the schema already documents buildId as 'The buildId returned by build_app'. The description references the same relationship but adds no new detail about the parameter's format, constraints, or usage beyond what the schema provides, so baseline 3 is appropriate.

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 verb ('Check'), a specific resource ('status of a PromptUI build'), and explicitly ties it to builds started with build_app. It also enumerates the possible status values, making the tool's purpose unmistakable and distinguishing it from build_app and list_builds.

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 clearly implies when to use this tool: after build_app, to check the resulting build's status. It does not explicitly contrast with list_builds or state when not to use it, but the 'started with build_app' condition provides enough contextual guidance for an agent to select it correctly.

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