Set a contact profile as default

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

Annotations already declare readOnlyHint=false and idempotentHint=true; the description adds the behavioral nuance that the change applies only to future orders and that the call 'returns the roles now applied,' which is useful state-disclosure beyond the structured fields. The mutation framing is consistent with readOnlyHint=false, so no contradiction exists.

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?

Two sentences with no waste: the first carries the action and return value, the second carries the impact scope and a pointer to the relevant sibling tool. Nothing repeats schema content or annotations.

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 mutation tool with full parameter coverage, an output schema, and idempotency annotations, the description covers the essential semantics: effect scope, return value, and how to obtain the id. The only gap is that none of the body's boolean fields are required, so an agent is not told what happens if an empty body is sent.

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%, so id and body are already fully described, including the source of the id and the meaning of each body boolean. The description's prose mapping of roles (registrant, admin, technical, billing) mirrors the schema's body fields (org, admin, tech, billing) without adding new detail. Baseline 3 applies because the schema does the heavy lifting.

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 action (making a profile the default) applied to a precise resource (contact profile) with an explicit scope (registrant, admin, technical or billing roles). The line 'This affects future orders, not domains already registered' sharpens the semantics further, and the verb-resource pairing clearly distinguishes it from siblings like eurodns_contact_save_profile and eurodns_contact_get_profile.

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?

Provides clear contextual guidance: the effect is limited to 'future orders, not domains already registered,' which tells an agent when this tool applies, and it points to eurodns_contact_get_profile for locating the profile. However, it does not explicitly contrast with eurodns_contact_save_profile or state when to prefer one contact operation over another.

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