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

Goes beyond the annotations by disclosing the two things an agent would worry about with a switch: the other variations are preserved and can be switched back to, and the change is immediate with no polling. Idempotency and non-destructiveness are already covered by annotations, so the added reversibility/immediacy context is the real contribution here.

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 core action is front-loaded in the first clause and the rest is supporting context in decreasing priority. The sentence 'Refinements and publishing target the active design, so use this to switch which design is live' is slightly circular and restates the verb, but it is short enough not to be a real cost.

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 three-parameter mutation with full schema coverage, non-destructive/idempotent annotations, and no output schema, the description covers what is needed: what changes, that prior state survives, and that the effect is immediate. Nothing an agent needs in order to call it correctly is missing.

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 100% and the schema already documents index as zero-based with a 'see list_variations' pointer, so the description's 'by its index (from list_variations)' largely repeats it. No added detail about the optional user_goal parameter or out-of-range index behavior, so baseline 3 applies.

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 resource (make a design variation the ACTIVE/live design for a site) plus the keying mechanism (index). This clearly separates it from generate_design_variation (creation), list_variations (enumeration) and patch_variation_content (editing) among the siblings.

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?

Gives a concrete reason to call it: 'Refinements and publishing target the active design, so use this to switch which design is live,' and points at list_variations as the source of the index. It stops short of stating exclusions or a full compare/contrast against e.g. patch_variation_content, so it is clear context rather than complete routing.

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