Describe the account IoT endpoints

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

Annotations already declare readOnlyHint, idempotentHint, and non-destructive, so the safety profile is covered. The description adds genuinely non-structured context: what each endpoint type is for, that resolution is per-account and per-region, and the practical failure mode this explains. It stops short of noting whether results are cached or how quickly endpoint changes propagate.

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?

Three sentences, front-loaded with the return value, then the endpoint taxonomy, then the operational implication. Every sentence carries distinct information and nothing is repeated from the schema or annotations.

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 zero-required-parameter, read-only lookup with no output schema, the description supplies what the tool returns (endpoint addresses) and the scoping rules (per account, per region), which is enough to call it correctly. It does not describe the shape of the returned object, though with no output schema that gap is minor.

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 enum parameter is already documented, so the baseline is 3. The description goes further by explaining what the enum values mean in practice (data vs. jobs vs. credential provider) and that the data endpoint is the MQTT/HTTPS address devices connect to, which is meaningfully more than the schema's short enum labels provide.

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: 'Returns the account-specific IoT endpoint addresses.' It then decomposes the resource into its variants (data, jobs, credential provider), which makes the tool's scope unambiguous. It does not explicitly contrast itself with any sibling, but no sibling in the list covers endpoints, so differentiation is inherent rather than stated.

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 line about endpoints being per-account and per-region being 'the usual cause of "the device connects but nothing arrives"' implies a diagnostic use case (connectivity troubleshooting), but usage is only implied. There is no explicit when-to-use statement, no when-not-to-use, and no named alternative tool for any adjacent task.

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