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

Annotations already declare it is a non-read-only, non-idempotent, open-world write. The description adds real context beyond that: the return payload (boxes, ids, warnings) and the approval/upload workflow that keeps the user's confirmation short. No contradiction with annotations. It does not say what happens to existing layouts or how warnings should be acted on.

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, purpose front-loaded before the workflow tip. The second sentence is dense but every clause carries information about the upload path. No 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?

No output schema exists, and the description does cover return values, which is good. But for a tool with a very large recursive layout-tree schema and eight loosely documented parameters, the description explains almost none of the core input structure, leaving the agent to infer it.

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 only 25%, and the description covers just two of eight parameters: 'layout tree' maps to root, and upload_id is explained in detail. The six spatial/verbosity parameters (x, y, width, height, verbose, artboard) get no mention, and the description gives no hint about the node vocabulary inside root, which is the hard part of calling this correctly.

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?

States a specific verb and outcome: 'Build a screen or section from a layout tree', and adds what is returned (boxes, ids, measured warnings). It is clearly distinguishable from list_layouts/inspect_layout/update_layout by the word 'build', though it never names those siblings explicitly.

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 only guidance is procedural: when running with a shell, offload fields to a JSON file and pass upload_id. That covers the upload path but says nothing about when to use create_layout versus update_layout or apply_layout_fixes, or what prerequisites (project, artboard) must be in place.

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