List custom metrics

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

Annotations already declare readOnlyHint=true and openWorldHint=true, covering the safety profile. The description adds the notable fact that there is no output schema but enumerates the return fields (parameter name, display name, unit, scope), which is genuinely useful. It still says nothing about pagination or volume, so a 3 is apt.

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?

One sentence, front-loaded with verb and resource, with the return fields in a compact parenthetical. No filler whatsoever.

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 no output schema, listing the returned fields in the description does real work; the single optional parameter is fully documented in the schema and annotations cover safety. Only the absence of pagination/volume expectations keeps it from a 5.

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?

Single parameter with 100% schema description coverage, including the default-property fallback, so the schema fully carries parameter meaning. The description adds nothing parameter-specific, which is the expected baseline here.

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 (List) and resource (custom metrics) and even names the fields returned, so the agent knows exactly what it gets. It does not explicitly differentiate itself from the near-sibling list_custom_dimensions, which keeps it short of a 5.

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?

No when-to-use guidance and no mention of alternatives such as get_metadata or list_custom_dimensions. The purpose is implied by the name, but nothing tells the agent when this is the right tool versus those siblings.

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