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

Annotations already indicate read-only and idempotent behavior. The description adds useful context about what the catalog contains (id, title, short description), which is not present in the schema. It does not discuss pagination or limits, but for a simple catalog list this is 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?

The description is a single sentence that is direct and front-loaded. It conveys the purpose and key options without wasted words.

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 no output schema, the description explains the return fields (id, title, short description), which is sufficient for a simple listing tool. The optional 'fields' parameter is described in the schema, so the description need not duplicate it, but the full output details are not elaborated.

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 100%, so the schema already documents all parameters. The description briefly mentions 'filtered by group or search' but adds no meaning beyond what the schema provides. This meets the baseline for full coverage.

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 'List' and clearly identifies the resource as the 'SCSS mixin catalog', including the output fields (id, title, short description). This distinguishes it from the sibling get_scss_mixin tool, which is likely for retrieving a single mixin.

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 provides clear context that this is for browsing the mixin catalog, optionally filtered by group or search. It does not explicitly mention when to use an alternative like get_scss_mixin, but the listing purpose is obvious and no exclusions are needed.

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