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

There are no annotations, so the description carries the behavioral burden. It usefully discloses that credentials will be visible in the AI conversation context and that authentication is required. However, it does not mention side effects, failure modes, or whether credentials are added to or replace existing provider credentials beyond the word 'additional.'

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 compact and front-loaded: first the operation, then a critical privacy warning, then the access/authentication requirement. Every sentence earns its place and there is no fluff.

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 mutating tool with three required parameters, a nested credentials object, and no output schema, the description covers the operation, precondition, authentication path, and a notable privacy risk. It omits possible provider identifier values and return behavior, but those are discoverable via sibling tools like get_dns_providers.

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 the schema already defines id, provider, and credentials. The description adds only the context that credentials are provider-specific and visible in-conversation; it does not enrich individual parameter meaning beyond the schema.

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 states a specific verb and resource: 'Add an additional DNS provider for verification to an already-verified domain.' It clearly distinguishes itself from initial-setup tools like connect_dns_provider or add_domain by emphasizing 'additional' and 'already-verified.'

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?

It gives clear prerequisites: the domain must already be verified, and a Proof account is required. It also explains the authentication flow via start_login. It does not explicitly list alternatives or when not to use the tool, but the context strongly implies the intended use case.

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