add_dns_subdomain

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

Annotations already declare readOnlyHint=false, destructiveHint=false, and openWorldHint=true, so the safety profile is covered. The description adds genuinely useful non-annotation context: the required pdns/edit permission and the backing API endpoint. It still does not say what happens on duplicate names or on failure.

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?

One compact sentence with the action front-loaded and zero filler. The parenthetical endpoint is the only arguably optional element, but it is short and aids traceability.

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 four-required-parameter mutation tool with no output schema, the definition covers the action and the auth requirement but omits edge-case behavior (duplicate subdomain, validation failures) and any note on the confirm flag's meaning beyond what the schema already states.

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 all four parameters (name, confirm, domain_id, server_id) are already documented in the schema, including the cross-reference to list_dns_domains. The description adds no parameter-level detail, 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 ("Add a subdomain") and even names the underlying API operation (pdns/add_subdomain). It is distinguishable from siblings like add_dns_domain, add_dns_zone, and edit_dns_subdomain, though it never explicitly contrasts itself with them.

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?

Usage is implied by the name and the permission note, but there is no explicit when-to-use guidance, no mention of the edit_dns_subdomain alternative, and no statement of prerequisites beyond the pdns/edit permission requirement.

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