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

Beyond the readOnly/idempotent annotations, the description discloses a key behavioral trait: content is conditional on premium statuscars. It specifies that metadata returns for everyone but ZPL source requires a plan with premium-template feature. This affects whether the agent can actually obtain the ZPL source, adding significant value over 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 carry all necessary information: the first front-loads the core purpose and return contents, the second handles the premium exception. No redundant phrasing or repetition of schema fields.

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 single-parameter, read-only, idempotent fetch with full schema coverage, the description is sufficient. It states what is returned, when ZPL source is unavailable, and the prerequisite for premium access. The absence of an output schema is mitigated by the explicit list of return components.

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 schema provides 100% coverage for template_id, including the helpful note that it comes from template_list. The description adds no additional parameter-level detail, so the baseline 3 applies because the schema already documents the single parameter adequately.

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 uses a specific verb ('Fetch'), a specific resource ('one catalog template'), and enumerates the returned components (metadata, preview image URL, ZPL source). It also distinguishes this tool from zpl_preview by noting the output is 'ready for' that tool, clarifying it fetches rather than renders.

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 clearly situates the tool in a workflow, implying it is used before zpl_preview by producing the ZPL source. It also explains the premium-template access rule. However, it does not explicitly name alternatives or state when not to use this tool, such as pointing to template_list for enumeration.

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