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

With no annotations, the description carries the full burden. It discloses that the tool creates a signed credential, which is the primary behavior, and notes enforced spend limits. However, it does not mention permissions required to issue, reversibility, or failure modes (e.g., invalid DIDs), which would be expected for a mutating credential-issuance 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 efficiently structured: a two-sentence purpose statement followed by a compact argument list. Every sentence adds value, and the format is scannable and front-loaded with the core purpose. No redundant filler or repetition of schema defaults beyond what is useful.

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 tool with an output schema and no nested objects, the description covers the essential behavior and all parameters. It lacks explicit discussion of authorization/preconditions and does not clarify how this tool relates to the other shopping tools (mt_shopping_info, mt_shopping_verify), but the overall meaning is clear enough for an agent to call it correctly in the intended scenario.

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 0%, so the description must fully compensate. It provides a dedicated Args section with human-readable explanations and examples for all six parameters, including units (spend_limit, currency), semantics (categories, validity_days), and DID formats. This adds substantial meaning beyond the bare schema titles.

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 names a specific resource (BuyerAgentCredential) and a specific action (issue/creates a W3C Verifiable Credential), and states the domain (shopping agent) that differentiates it from other issue_vc siblings like mt_skill_issue_vc and mt_travel_issue_vc. It clearly distinguishes this issuance tool from verification or info tools in the same family.

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 clear context for when it is used: to authorize a shopping agent to make purchases on behalf of a human with spend limits. It does not explicitly name alternatives or state when not to use it, but the purpose is specific enough to infer it should be used only for issuing shopping credentials rather than verifying or querying them.

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