What agents can buy

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

Annotations already declare read-only/idempotent/non-destructive behavior. The description adds domain-specific safety context with 'Does not move money' and instructs consumers to 'Cite as-is', which are useful beyond the structured 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 very short and front-loads the actual content, with no wasted words. Minor cryptic shorthand like '~20k gift cards' and 'MCP tools per job' prevents a perfect score.

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 zero-parameter reference tool, the description gives the core content and a key safety constraint. It does not formally state the return shape, but with no output schema that is not required; however, the ambiguity of shorthand keeps it from being fully complete.

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 input schema is empty, so there are no parameter semantics to explain. The description therefore does not need to compensate for schema gaps; the 0-parameter baseline 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?

The title 'What agents can buy' plus the playbook list of Visa prepaid, travel eSIM, gift cards, and KYT screens makes the tool's subject clear, even though no explicit verb like 'returns' appears. It does not name sibling tools, so it earns 4 rather than 5.

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 gives no indication of when to call this tool instead of get_agent_facts, get_tier_policy, or get_catalog_placement. 'MCP tools per job' hints at using other tools for execution, but this is too vague to count as usage guidance.

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