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

Annotations already declare readOnlyHint=true and destructiveHint=false, so the safety profile is covered. The description adds value by disclosing exactly what data will be retrieved (MJML source, rendered HTML, tags, usage metrics), which is useful behavioral context beyond the annotations. It does not mention any potential side effects or limitations, but these are not pertinent given the read-only nature. No contradiction with 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?

The description is a compact, front-loaded paragraph that opens with the core action and return values, then provides sequencing context and next steps. Every sentence contributes meaningful information with no redundancy or fluff. It is appropriately sized for the tool's simplicity.

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 tool with full schema coverage and no output schema, the description is complete. It specifies what is returned, when to call it, and what to do next. An agent has all necessary information to decide when and how to invoke it correctly, without needing additional details.

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%: the template_id parameter has a description that explains its purpose and how to obtain valid IDs (from nevent_list_templates). The tool description does not add any additional parameter semantics beyond what the schema already provides. Since the schema fully documents the parameter, the baseline of 3 is correct.

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 verb ('Retrieve') and the resource ('email template'), and enumerates the specific content returned (MJML source, rendered HTML, tags, usage metrics). It distinguishes itself from sibling tools by explicitly framing the retrieval as the second step after nevent_list_templates and before nevent_update_template or nevent_create_campaign, making its role in the workflow 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 gives explicit when-to-use context: 'Call this after nevent_list_templates when the user wants to inspect, copy, or modify a template.' It also names the next-step alternatives (update or create campaign). It does not explicitly mention when not to use it (e.g., if only a preview is needed, nevent_preview_template might be more appropriate), but the guidance is clear enough for typical usage. A score of 4 is appropriate given the lack of explicit exclusions.

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