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

No annotations are provided, so the description carries the full behavioral disclosure burden. It does not state that this is a pure, side-effect-free transformation, does not describe the returned CSS format, and does not mention how zero/default values or invalid inputs are handled.

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 a single, front-loaded sentence with no filler. Every word contributes to identifying the operation and its inputs.

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 four-parameter transformation tool with no output schema and no annotations, the description is too thin. It does not explain the output format, the ordering or abbreviation meaning of the corner parameters, or the default behavior when inputs are omitted.

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 0%, and the four abbreviated parameters (bl, br, tl, tr) are undocumented in the schema. The description adds the unit ('px') and the general concept ('corner radii'), but never maps the abbreviations to bottom-left, bottom-right, top-left, and top-right, nor mentions the default of 0.

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 states a specific verb and resource: 'Build a CSS border-radius value'. It also identifies the input domain ('four corner radii in px'), which makes the tool distinguishable from most siblings. It does not explicitly differentiate itself from nearby siblings like css_box_shadow_build, but the resource is clear.

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 gives no when-to-use or when-not-to-use guidance and names no alternatives. It only states the mechanical purpose, leaving the agent to infer that this is the tool for constructing a border-radius value when other CSS formatting tools exist.

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