check_domain_credentials

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

Annotations only declare readOnlyHint=true, so the description carries most of the load and adds genuinely useful context: it is a non-mutating credential probe and it requires a Proof account, with two concrete paths to authenticate (PROOF_API_KEY or start_login). It does not describe what a failed check looks like or any rate limits.

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 purpose in the first sentence, followed by usage and then access notes. All three sentences carry distinct information; the ACCESS block could be tightened but is not wasteful.

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 one-parameter, no-output-schema read tool, the description covers purpose, sequencing, and the authentication prerequisite. The main gap is that it does not say what the check returns or how to interpret a negative result, but that is a minor omission for a read-only probe.

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% for the single 'id' parameter ('Domain ID to check credentials for'), so the schema already does the work. The description adds no format or syntax detail beyond it, making the baseline 3 appropriate.

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?

Specific verb+resource: checking whether stored DNS credentials have access to a domain. It distinguishes itself from the verification siblings by framing itself as a pre-flight credential test, though it does not explicitly name the sibling it differs from (e.g. verify_domain_with_credentials).

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?

Explicitly states when to use it: 'Use before triggering verification to confirm the credentials work.' That gives a clear precondition and ordering relative to the verification flow. It does not spell out when NOT to use it, so it stops short of a 5.

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