cocos_start_preview

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

With no annotations provided, the description carries the full burden of behavioral disclosure. It effectively describes key traits: the tool starts a server, returns specific data ({port, url, serving}), is idempotent, and replaces existing servers on the same port. However, it lacks details on error conditions, timeout behavior, or server lifecycle management, which keeps it from a perfect score.

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 front-loaded with the core purpose in the first sentence, followed by return values and behavioral notes in subsequent sentences. Every sentence adds value without redundancy, making it efficiently structured and appropriately sized.

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?

Given the tool's complexity (starting a server with 3 parameters) and no annotations or output schema, the description does well by covering purpose, prerequisites, idempotency, and return values. However, it lacks details on error handling or server configuration, which are relevant for a mutation tool, preventing a perfect score.

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 schema description coverage is 0%, so the description must compensate. It mentions the 'build/<platform>/ directory', which hints at the 'platform' parameter, and 'port' in the idempotency note, but does not explain 'project_path' or provide format details. Since it adds some context but not full parameter semantics, a 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 clearly states the specific action ('Start a local HTTP server') and the resource being served ('the build/<platform>/ directory'), distinguishing it from sibling tools like 'cocos_build' (which prepares the build) or 'cocos_stop_preview' (which stops the server). It provides a precise verb+resource combination that is not tautological.

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 states when to use this tool ('Run `cocos_build` first') and provides a clear prerequisite. It also distinguishes it from alternatives by noting idempotency and replacement behavior, which helps the agent understand when to invoke it versus other server-related tools.

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