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

Annotations already cover safety (readOnly, idempotent, non-destructive, closed-world), yet the description still adds substantial context: required billing read scope, the claimed-workspace requirement, an explicit 403 for sandbox self-registration keys, and the early-access empty state returning released=false. That is exactly the extra behavioral detail structured fields cannot express.

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?

Purpose and returned fields are front-loaded, and each later sentence contributes new information (early-access behavior, credential scope, workspace claim). The prerequisite sentences are long and somewhat run-on, but no sentence is redundant.

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?

There is no output schema, so the description compensates by enumerating returned fields, describing the empty/early-access response, and listing every precondition that can block the call. An agent has everything needed to call it and interpret the result.

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% with the single enum parameter fully documented, so the schema already carries the burden. The description restates the status values (active, inactive, archived) but adds no syntax or semantics beyond the schema's enum, so the baseline 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 and resource ("List the credit bundles your workspace sells") and enumerates exactly which fields come back (id, name, code, price, billing frequency, credits, rollover, status), which implicitly separates it from list_credit_bundle_subscriptions. It stops short of naming a sibling to disambiguate against, so the distinction must be inferred from the field list.

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 only implied by the resource description; there is no explicit "use this when..." or "not for..." clause, and the closest sibling (list_credit_bundle_subscriptions) is never mentioned. The prerequisites given are about access, not about choosing this tool over another.

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