Update domain contact

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

Annotations already declare destructiveHint=true and readOnlyHint=false, and the description usefully adds the auth requirement (domains:manage with an API key). It does not disclose the mutation semantics that matter most for a 16-field update: whether omitted fields are preserved or cleared, and whether changing is_default affects other contacts.

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 short sentences, front-loaded with the action and followed by the permission constraint. Nothing is padded, though the brevity comes partly from under-specification rather than tight editing alone.

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 destructive multi-field mutation with no output schema, the definition covers the primary action and auth requirement but leaves the partial-update/field-replacement behavior and any side effects of is_default unstated. Adequate but with a clear gap an agent would care about.

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% and the schema already documents every one of the 16 fields, including the individual/business conditional requirements and the enum. The description adds no parameter-level meaning beyond what the schema provides, so the 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?

Specific verb+resource ("Update an existing domain contact") that cleanly separates it from create_domain_contact, delete_domain_contact and list_domain_contacts. It does not, however, explicitly name those siblings or scope what a contact covers.

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 only conditional guidance is the domains:manage permission requirement. There is no statement of when to use this versus create_domain_contact or delete_domain_contact, nor any prerequisite (e.g. contact must already exist and belong to the account).

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