Send a customer a sign-in link. Money is integer minor units (cents). Calling this changes nothing: it returns a preview of what would change and a confirmation link. Only the merchant, on that page, can make it happen.
| Name | Required | Description | Default |
|---|---|---|---|
| Yes | The customer's email, as on their file. Shoppers have no password; this sends the link that signs them in. |
Changes observed during successful MCP inspections.
Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
Annotations declare readOnlyHint=false, but the description explicitly states 'Calling this changes nothing', a direct contradiction. Despite adding useful context about the preview and merchant confirmation, the contradiction mandates a score of 1.
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 contains an irrelevant sentence: 'Money is integer minor units (cents).' This is unrelated to the tool and adds confusion. The rest is reasonably concise but the extraneous content hurts.
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 simple one-parameter tool with annotations, the description covers the preview behavior and confirmation step. However, the contradiction with annotations and the extraneous sentence reduce completeness.
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% and the single email parameter is fully documented. The description adds no parameter-specific information, and the irrelevant sentence about money does not help.
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: 'Send a customer a sign-in link.' The purpose is clear and distinguishable from most siblings, though it does not explicitly name alternatives.
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?
No explicit when-to-use or when-not-to-use guidance, and no alternatives are mentioned. It implies usage by describing the action but offers no routing context.
Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.
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