Hug, fill or fix a size

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

Annotations already mark this as destructive and not read-only. The description adds behavioral meaning by explaining what HUG, FILL, and FIXED do to the child. It does not elaborate on destructive side effects, but the annotations carry that responsibility, so the added semantics are sufficient.

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 deliver the core concept, define all enum values, and provide a routing rule away from a sibling tool. Every sentence earns its place and the key guidance is front-loaded.

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 focused mutator with few parameters and no output schema, the description gives the enum semantics, the relevant context (auto-layout frame), and sibling disambiguation. It could add a note about prerequisites, but the essential information for correct invocation is present.

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 only 33%, but the description meaningfully defines the three enum values shared by the vertical and horizontal parameters. NodeId is already well described in the schema, and the parameter names make the axis association clear.

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 title and description clearly identify the tool as controlling child sizing behavior inside auto-layout frames, distinguishing HUG, FILL, and FIXED. It also explicitly differentiates itself from figma_set_bounds, making the tool's purpose and scope immediately understandable.

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 that this tool, not figma_set_bounds, is the correct way to set widths inside auto layout. This directly gives the agent a when-to-use and when-not-to-use signal with a named alternative.

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