set_domain_case

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

Annotations already declare readOnly=false, idempotent=true, destructive=false, so the safety profile is covered. The description adds genuinely useful behavior beyond that: the forward-only effect on future writes, the pre-merge collision preview in the dashboard path, and the return shape {"mode": ...}.

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?

Three tight sentences with the scope constraint front-loaded and no filler. There is mild redundancy between 'for every domain written from now on' and 'This only governs new writes,' but nothing is padded.

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 one-parameter, non-destructive, idempotent setter with rich annotations, the description covers the forward-only semantics, the alternative path for existing data, and the return value despite no output schema. An agent has everything needed to call it correctly.

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 itself enumerates 'preserve', 'lower', and 'upper' with their effects, so the description is not required to document mode. It adds no syntax or edge-case meaning beyond the schema, making the baseline 3 appropriate.

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 — setting the store's domain-casing policy — and scopes it precisely to 'every domain written from now on.' It distinguishes this from the retrospective normalization path, though it never names its read-side sibling get_domain_case, leaving that pairing to inference.

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?

Explicitly bounds when this applies ('only governs new writes') and routes the agent elsewhere for the excluded case ('to bring already-stored domains into line, run the "Normalize domains" action in the admin dashboard'). That is a complete when/when-not 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.