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

The annotations already establish that this is a non-read-only, open-world, non-idempotent, non-destructive operation. The description adds useful behavioral context: it creates a pending domain and returns DNS records, and it warns against a dangerous misconfiguration involving Shopify checkout. It does not mention auth requirements or duplicate-call behavior beyond the idempotency annotation.

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 three tight sentences, front-loaded with the action and immediate result. The warning is placed after the core behavior and every sentence contributes useful information.

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 two-parameter mutation with no output schema, the description is nearly complete: it explains the side effect, the returned DNS records, and a critical exclusion. The only minor gap is that it does not explicitly route the agent to the verification or status sibling tools.

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 0%, but the schema itself provides formats and a domain pattern. The description adds only high-level meaning by mapping the domain to a Replo site, without explaining siteId or domain constraints beyond that. This is minimally adequate but does not fully compensate for the missing parameter descriptions.

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: beginning connection of a custom domain to a Replo site. It also clarifies the immediate effect by saying it creates a pending domain and returns the DNS records needed before verification. This is enough to distinguish it from status-checking and verification siblings.

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 clearly indicates this is the starting step for custom-domain setup, with verification only possible afterward. It also gives a strong exclusion: never connect a Shopify store's primary domain. It does not explicitly name verify_custom_domain as the next tool, so it stops short of full alternative routing.

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