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

readOnlyHint=true already declares the read-only safety profile, so the description does not need to restate it. It adds only the REST endpoint mapping ('GET /metrics') and says nothing about pagination behavior at the call level, rate limits, or result ordering, so it adds modest value over the annotations.

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 short sentences, zero filler, with the core purpose front-loaded and the API endpoint mapping trailing. Nothing here needs to be trimmed.

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 simple, annotation-covered, parameter-complete list tool, the description is nearly sufficient; no output schema exists but the cursor description implies paginated returns. It could note what the listing returns or max page size, but nothing essential for a correct call is missing.

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 description coverage is 100% – both 'limit' (with range and default) and 'cursor' (with source of the value) are fully documented in the schema. The description adds no parameter-level detail, so the baseline of 3 applies.

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 ('billable metrics') with scope ('configured in the Orb account'), so an agent immediately knows what it retrieves. No sibling tool covers metrics, so differentiation is inherent, but the description never explicitly contrasts with the other orb_list_* tools, capping it below 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?

Usage is implied by the enumeration semantics and the absence of a competing sibling, but there is no explicit when-to-use statement, no prerequisites, and no exclusions. It is the minimum viable level: an agent can infer the use case but gets no routing guidance.

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