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

With no annotations provided, the description carries the behavioral disclosure burden. It states that authentication is required, which is useful, and the verb 'List' clearly implies a read-only operation. It does not, however, describe any behavioral nuances such as whether the result includes only exact matches, whether subdomains are included, or what the response shape will be.

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 two short sentences with no filler. It front-loads the core purpose, then adds the authentication requirement and the key parameter detail. Every sentence contributes meaningful guidance.

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 straightforward listing tool with only two parameters, the description covers the essential context: what it returns, that authentication is needed, and which parameter is required. There is no output schema, but the phrase 'List all host/glue records associated with a domain' sufficiently communicates the expected result. A small gap is the lack of any mention of the sessionKey parameter, though the schema covers it.

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?

The schema only documents sessionKey, leaving domain with no description, so schema coverage is only 50%. The description compensates for the undocumented domain parameter by providing a clear example: 'e.g., \'example.com\''. It also reinforces that domain is required. The sessionKey semantics are fully handled by the schema, so the description does not need to repeat them.

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 and resource: 'List all host/glue records associated with a domain.' This clearly distinguishes it from siblings like getDnsRecord, listDnsRecords, and getContactsForDomain. The purpose is immediately understandable without needing to inspect the schema.

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?

The description gives useful context: it is for listing host/glue records for a domain, requires authentication, and the domain parameter is required. However, it does not explicitly state when to prefer this over sibling tools such as listDnsRecords or getDnsRecord, or when it should not be used. The usage is mostly implied rather than explicitly guided.

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