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

The description claims a 'preview' action, which typically implies no state changes, but the annotations set readOnlyHint to false, indicating the tool may modify state. This is a direct contradiction. The description adds no further behavioral context beyond the annotations, and the contradiction undermines trust.

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 short sentence, which is concise, but it is under-specified to the point of vagueness. Brevity is not useful when it omits essential information; the sentence does not earn its place because it adds little value over the tool name and title.

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 3 parameters (1 required), no output schema, and minimal annotations. The description should clarify what the preview returns, how sample variables are populated, and how email_type influences the preview. None of this is provided, leaving the tool severely under-specified for an agent to call correctly.

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?

With schema description coverage at 0%, the description must explain the parameters, but it only mentions 'sample variables' without clarifying the role of email_type, request_id, or idempotency_key. The enum values for email_type are not explained, and the optional parameters are completely unaddressed.

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 states the verb 'preview' and the resource 'email template', so the core action is identifiable. However, the phrase 'for sample variables' is vague and does not clarify what 'candidate' means or how it differs from other preview tools like yardstick_email_templates_preview_customization. It lacks specificity to distinguish it from siblings.

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 alternatives. It does not mention any conditions, prerequisites, or related preview tools. An agent is left without context for selecting this tool over the many other preview tools in the sibling list.

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