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

With no annotations provided, the description carries the full burden of behavioral disclosure. It mentions that warnings indicate what was stripped and what would not render, which is a key behavioral trait. However, it does not explicitly state that the operation is read-only or has no side effects, which would be expected for a preview tool. It also doesn't mention permissions or reversibility. The description adds some value but leaves gaps in behavioral transparency.

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 two sentences with zero wasted words. The primary purpose is front-loaded in the first sentence, and the second sentence adds a crucial detail (warnings) that the agent needs to know. It is concise, structured, and every sentence earns its place.

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's moderate complexity (7 parameters, nested objects) and the absence of an output schema, the description provides sufficient context for an agent to understand its primary use: previewing a template before sending. It mentions the return of warnings, which is key. However, it does not explicitly describe the full return structure (e.g., whether it returns the rendered HTML along with warnings) or elaborate on the relationship between the required parameters. The description is adequate but could be more explicit about the output.

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 covers 100% of parameters with descriptions, so the baseline is 3. The description does not add any additional meaning to the parameters themselves. It does not explain how 'blocks', 'variables', or 'values' interact, nor does it clarify the purpose of each parameter beyond the schema. Since the schema already does the heavy lifting, the description adds no extra value here.

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 clearly states the tool's action: 'Compile and render a safe template preview.' It specifies the resource (template preview) and the verb (compile and render). It also differentiates from sibling tools like template_get or template_publish by emphasizing 'safe' and 'preview', implying it's not a retrieval or a publish action. This is specific and unambiguous.

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 a clear usage context: 'read it before publishing rather than after sending.' This tells the agent when to use the tool (before publishing) and hints that it's for validation. However, it does not explicitly name alternative tools or state when not to use it, such as 'use template_get to retrieve a stored template.' The guidance is helpful but not exhaustive.

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