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

Adds substantial context beyond the annotations: the server throttles rapid re-checks (why not to poll), the 'first-to-verify wins' claim semantics that explain why destructiveHint=true, and the side effect of starting certificate issuance. This directly informs the agent's calling strategy.

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?

Front-loaded with the core action, then layered with operational warnings and next steps. Dense but every sentence carries distinct guidance; slightly long for a one-parameter tool but no filler.

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?

An output schema exists, so return values need not be re-explained, yet the description still references the 'verified' field behavior and the cert lifecycle states. For a network-dependent, side-effecting verification tool, an agent has everything needed to call 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 coverage is 100% and the single hostname parameter is already documented with an example in the schema. The description adds no format or syntax detail beyond what the schema provides, so the 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: 'Check the DNS TXT challenge for a claimed domain and, on success, take the global (hostname -> tenant) binding and start certificate issuance.' This clearly distinguishes it from siblings create_custom_domain (which initiates) and get_custom_domain (which reads state).

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?

Explicit when-to-use: 'Call this ONCE after the human confirms they have added the DNS records from create_custom_domain.' Names the preconditions, the failure path ('tell the human it may take a few minutes and check back later'), and the alternative for monitoring ('Read get_custom_domain to watch the certificate go from CERT_PENDING to ACTIVE').

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