list_metric_namespaces

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

No annotations are provided, so the description carries the burden. It discloses the mechanism (querying unique _contentType values) and provides examples, but it does not mention the effect of from_time, potential cost, or safety profile. It adds some context beyond the name but lacks depth.

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 paragraphs, front-loaded with the core purpose and followed by a concise explanation. Every sentence adds value.

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 an output schema present and a simple optional parameter, the description sufficiently conveys the tool's scope and discovery mechanism. It could be slightly more explicit about when to use it, but overall it's complete for a simple listing tool.

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 input schema has one parameter with 100% description coverage, so baseline is 3. The description does not mention from_time or its role, but the schema already documents it. No additional meaning added.

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 clearly states 'List metric namespaces' with a specific verb+resource, and clarifies what namespaces are via examples (HostMetrics, AwsCloudWatch). This distinguishes it from sibling tools like list_metric_definitions by explaining that namespaces are based on unique _contentType values.

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 implies usage for discovering available metric sources, but it does not explicitly state when to use this tool versus alternatives like query_metrics or list_metric_definitions. No exclusions or alternative references.

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