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

Annotations already cover the safe-read profile; the description goes further by disclosing the authorization model — premium templates return metadata to everyone, but ZPL requires an API key whose plan includes the premium-template feature. That conditional-content behavior is exactly what an agent needs and is not derivable from the 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?

Two sentences, front-loaded with the verb and resource, with the premium caveat following. The nested em-dash parentheticals make it denser than necessary, but no sentence is filler.

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?

There is no output schema, so the description carries the return-value burden and does so at the level of the three payload pieces. The internal structure of 'metadata' is left unspecified, a minor gap for a read-only single-record fetch.

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 parameter is already documented as 'Template id from template_list (the id, not the display name)'. The description adds no additional semantics about the id, so the baseline 3 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?

States a specific verb ('Fetch') and a scoped resource ('one catalog template') and enumerates what comes back: metadata, preview image URL, and conditionally the ZPL source. The premium/non-premium split further narrows what a given call actually returns, so an agent knows exactly what it is asking for.

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?

Implies downstream use ('ready for zpl_preview') and states the access precondition for premium templates. It does not explicitly say when to use this instead of template_list, but that routing is covered by the schema note pointing at template_list as the id source.

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