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

The annotations cover the safety profile (not read-only, not destructive, not idempotent), and the description adds genuinely new behavior: it returns the DNS TXT record and CNAME target, and the domain begins routing only after TXT verification. That is real lifecycle context beyond the annotations. It omits what happens on a duplicate call (relevant given idempotentHint=false) and any permission requirements, so it is not a 5.

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 sentences, zero filler, and the action is front-loaded before the return-value detail. Every clause carries information the agent would otherwise have to guess.

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?

With no output schema, the description correctly spends its space explaining the return value and the verification dependency, which is what an agent needs for this simple two-parameter tool. The remaining gap is the missing handoff to verify_domain and the unstated domain format.

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 coverage is only 50%: project_id is documented in the schema while the schema also constrains its pattern, but the domain parameter has no description, no pattern and no format hints. The description adds nothing about domain syntax (bare hostname vs. URL, subdomains, apex domains), which is exactly the meaning the agent needs when the schema is silent.

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 uses a specific verb plus resource ('Attach a custom domain to a DenkOps project'), which is clearly distinct from list_domains, remove_domain and verify_domain. It stops short of explicitly naming those siblings, so an agent must infer the boundary from the verb alone.

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 'Attach' – the domain does not yet exist on the project – and the description notes the domain only starts routing after TXT verification. However, it never points to verify_domain as the follow-up step or states what happens if the domain is already attached, leaving the agent to infer the workflow.

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