add_dns_subdomain

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

Annotations already declare readOnlyHint=false and destructiveHint=false, indicating a non-destructive write operation. The description adds the permission requirement (pdns/edit) and the internal endpoint name, which are beyond the structured metadata. It does not contradict the annotations and provides useful operational context about access control.

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 description is two concise sentences with no filler. The primary action is front-loaded, followed by the permission requirement. Every word contributes to understanding the tool's function, and the internal endpoint reference adds precision without bloat.

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 straightforward add operation with a required confirm flag and schema that already references list_dns_domains for domain_id, the description provides adequate context. It covers the action and permission but does not mention potential failure modes (e.g., duplicate subdomain) or side effects beyond the table insertion. However, given the simplicity and existing structured data, the description is sufficiently complete for an agent to invoke 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 description coverage is 100%, so each parameter (server_id, domain_id, name, confirm) is already documented with a short description. The tool description adds no additional meaning beyond the schema, such as relationship between parameters or formatting rules. Per the calibration baseline, a score of 3 is appropriate when the schema carries the parameter documentation burden.

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?

The description clearly states the action ('Add a subdomain'), the resource ('to the subdomains table'), and even names the underlying API endpoint (pdns/add_subdomain). This distinguishes it from sibling tools like add_dns_domain (which adds a domain) and edit_dns_subdomain (which modifies). An agent can immediately understand what this tool does without inspecting the schema.

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 description provides the essential prerequisite (requires pdns/edit permissions) but does not explicitly mention when to use this tool versus alternatives like add_dns_domain or edit_dns_subdomain. While the purpose is clear from the name, there is no explicit guidance on selection criteria or exclusions, leaving the agent to infer usage context from sibling tool names.

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