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

The readOnlyHint annotation already covers the safe read-only nature, and the description reinforces it by citing the GET endpoint. The description adds the timeframe concept but does not explain aggregation behavior, grouping effects, or timezone handling, so it adds only modest context beyond 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?

The description is two short, front-loaded sentences with no filler. The primary purpose comes first, and the API endpoint reference is useful supplementary context.

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?

Given the 100% schema coverage, the readOnlyHint annotation, and the explicit endpoint, the description is largely complete for invoking the tool correctly. The main gap is the absence of any detail about the response shape, especially since there is no output schema, but the parameters and purpose are sufficiently 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 description coverage is 100%, so all five parameters are documented in the schema itself. The description does not add any parameter-level meaning beyond what the schema already provides, so the baseline score of 3 is appropriate.

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 the operation: 'Get costs for a subscription over a timeframe,' naming both the resource (subscription) and the specific action (get costs). This distinguishes it from sibling tools like orb_get_subscription_usage and orb_get_customer_costs.

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 the tool is for fetching subscription cost data over a time range, but it gives no explicit guidance on when to prefer this over related tools such as orb_get_subscription_usage or orb_get_customer_costs. No alternatives or exclusions are mentioned.

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