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

Annotations already declare readOnly, idempotent, and non-destructive hints. The description adds the 'copy-ready CSS string' output trait and explains the layer structure, which provides useful behavioral context beyond the annotations. No contradiction with annotations.

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 two sentences with front-loaded purpose, then parameter details, then output format. Every word earns its place; there is zero waste and no redundancy with the schema.

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?

With only one required parameter, a detailed schema, an output schema present, and annotations providing the safety profile, the description is fully sufficient. The output format is explicitly stated, so an agent can correctly invoke the tool without additional context.

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 covers 100% of parameters with detailed descriptions for each field (offset, blur, spread, color, inset). The description only lists the field names without adding new meaning, so the baseline score of 3 is appropriate as the schema already provides full parameter semantics.

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 ('Build') and names the exact resource ('CSS box-shadow declaration'), clearly distinguishing it from sibling tools like color-converter or hex-to-rgb. It also specifies the scope ('one or more shadow layers'), leaving no ambiguity about its function.

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 clearly implies the use case (generating box-shadow CSS from layers), which is obvious from the context. However, it does not explicitly state when not to use this tool or name alternative tools. Since no sibling tool overlaps, this is acceptable but lacks explicit exclusion guidance.

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