list_metrics

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

Annotations already convey readOnlyHint=true and openWorldHint=true, so the safety and open-world nature are covered. The description adds a small amount of behavioral context by framing this as a lookup for revenue reporting, but it does not reveal additional characteristics such as pagination or whether the list may be partial.

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?

Two tight sentences: the first defines what the tool returns, and the second explains why an agent would call it. There is no filler or repetition of the schema, and the most useful information is front-loaded.

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, read-only listing tool with no output schema, the description gives enough context for an agent to invoke it correctly and understand the intended outcome. It stops short of describing the response structure or pagination, but the stated purpose of finding a metric ID makes the expected outcome reasonably clear.

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 'account' parameter is described as 'Account name'. The description doesn't add much beyond that, aside from general context that the metrics belong to a Klaviyo account and that the result will contain metric IDs. This meets the baseline for schema-heavy descriptions.

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 a specific verb ('List') and resource ('available metrics for a Klaviyo account'), and immediately ties it to a practical use case: finding the 'Placed Order' metric ID for revenue reporting. This distinguishes it from sibling list tools, which target different resources.

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 a clear context for when to use the tool: when the agent needs to look up a metric ID, specifically the one for 'Placed Order'. It doesn't explicitly mention alternatives or when not to use it, but the purpose is concrete enough to route an agent correctly.

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