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

The description and input schema describe a purchase that changes credit ownership after settlement, but the annotations declare readOnlyHint=true. This is a direct contradiction: the description does not correct or qualify the read-only signal and fails to disclose the actual mutating/payment side effects of the operation.

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 compact and front-loaded with the legacy status and preferred alternatives. Every clause carries information, though the phrase 'OFF TABLE as wealth and primary agent buy' is awkward and slightly ambiguous.

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?

The tool has only two well-documented parameters and an output schema, and the usage policy is covered. However, the readOnlyHint annotation directly contradicts the buy semantics, and the description never clarifies that calling this tool will actually execute a purchase and change state. That is a critical completeness gap for safe agent use.

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?

The schema description coverage is 100%, so the description does not need to explain bundle or agent_id. It adds policy context by noting bundles remain for volume validates only, but no additional technical parameter semantics beyond the schema. Baseline 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 identifies the resource as LEGACY prepaid credits and implicitly the buy action via the title and 'primary agent buy', while distinguishing this tool from sqlguard_challenge and Gateway invoice. However, it never plainly states 'purchases a credit bundle'; the meaning is inferred from the name and schema rather than explicitly described.

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 explicitly tells agents to prefer sqlguard_challenge for an exact $100 unlock or Gateway invoice for $299, and restricts micro|starter|builder|team bundles to volume validates only, not standard authorization. This is clear, actionable when-to-use and when-not-to-use guidance with named alternatives.

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