zpl_preview

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

No annotations are provided, so the description carries the behavioral burden. It usefully discloses that this is a server-side render via an external API and warns that output is not a guarantee of physical printer output. However, it does not describe return format, error behavior, or external-API implications such as latency or failures.

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?

Two sentences with no filler: the first states the core action, and the second delivers a relevant caveat. It is appropriately front-loaded and every phrase 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?

For a moderate external rendering tool with all parameters documented and no output schema, the description provides the essential selection and invocation context: what it renders, how, and a key limitation. It is slightly light on post-call behavior (how the PNG is returned or errors surface), but the core context is present.

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 description coverage is 100%, with each parameter already documented including defaults and constraints. The description adds no parameter-level nuance beyond identifying the input as ZPL label code, so the baseline 3 is appropriate.

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 opens with a specific verb and resource: 'Render ZPL label code to a PNG image via the Labelixa API.' It adds a clear differentiating qualifier ('SERVER-SIDE render for inspection'), which makes it easy to tell apart from validation/explanation siblings like zpl_validate and explain_zpl even without naming them.

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 clear usage context ('for inspection') and an explicit exclusion: it is 'not a guarantee of how a specific physical printer will output the label.' It does not name sibling alternatives or state when to prefer zpl_validate, but the intended use case is reasonably clear.

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