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

With no annotations provided, the description carries the full burden of disclosing behavioral traits. It only says 'Return', which weakly implies a read operation, but does not state whether authentication is required, if it has side effects, or if it is idempotent. The description adds no behavioral context beyond what is inferred from the tool name.

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 a single sentence, but it is dense with a long list of contract aspects (purchase, payer-ownership, issuance, economics, credential-security). While concise in word count, the readability suffers from the packed enumeration. A clearer structure (e.g., bullet points) could improve comprehension without sacrificing brevity.

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 tool has no parameters and no output schema, the description lists several components of the contract, providing some context. However, it does not mention the return format, whether the contract is a JSON object or a string, or any authentication or preconditions. For a simple getter, this is adequate but not richly complete; the calibration for a comparable tool (get_calls) provides more context about scope and filtering.

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 tool has zero parameters and schema description coverage is 100% (trivially). The description does not add parameter semantics because there are no parameters to describe. 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 specifies the verb 'Return' and identifies the resource as a 'virtual-card direct x402 purchase, payer-ownership, issuance, economics, and credential-security contract'. This clearly distinguishes it from sibling tools like 'get_agent_contract' or 'get_esim_contract' by explicitly targeting the card contract.

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 provides no guidance on when to use this tool versus its siblings. It does not mention scenarios, prerequisites, or exclusions. For example, it could say 'Use this to retrieve the contract for a virtual card; for an agent contract use get_agent_contract.' The lack of such guidance makes it harder for an agent to choose correctly among the many get_* contracts.

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