Open the layout-debug window

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

With no annotations, the description carries the full burden and does well: it discloses the lazy-start side effect, the interactive model (user selects/moves elements and writes requests), and the return payload (window URL plus how to listen). It does not cover failure modes (e.g., server start failure), permissions, or how the window is closed, leaving some behavioral gaps.

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 sentences, front-loaded with the action, then what the window provides, then what gets returned. Given the absence of an output schema, the mention of the return value earns its place rather than being filler.

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-parameter tool with no output schema, the description covers what the tool does, what appears in the window, what is returned, and the follow-up sibling. The main omission is any statement about window lifecycle or error handling, which would make it fully self-contained.

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 tool takes zero parameters, so the baseline of 4 applies; there is nothing for the description to disambiguate, and it correctly spends no words on parameters.

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 uses a specific verb+resource pair ('Start the layout-debug server ... and open its window in the browser') and immediately clarifies the scope by naming the follow-up sibling wait_for_message, so an agent can separate this from reply_in_window or pending_requests without opening any schema.

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?

It gives a clear usage condition ('Start the layout-debug server if it is not running') and routes the agent to the correct next step ('how to listen for the user's messages (wait_for_message)'). It stops short of an explicit when-not case or stating that a window already open is reused, but the context for calling it is unambiguous.

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