Create Newsletter

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

Annotations indicate idempotentHint=true and destructiveHint=false, and the description aligns by stating it creates a draft (non-destructive). It adds context: Shipmail renders blocks to email-safe HTML/text, and drafts must pass preflight before scheduling. The differentiation between 'styled' and 'plain' styling is explained, providing behavioral insight beyond 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 concise, consisting of four sentences that front-load the purpose, then provide key usage guidance and behavioral details. Every sentence adds value without redundancy.

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?

While the description covers core creation workflow (body content, styling, preflight requirement), it omits guidance on several parameters (e.g., preview_text, send_window_hours, archive_visibility). Given the tool's complexity (12 parameters, 4 required) and the existence of an output schema, the description is partially complete but leaves gaps.

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?

With schema description coverage at 50%, the description adds meaning by grouping body content parameters (blocks, body_html, body_text) and clarifying the requirement for at least one. However, it does not explain other parameters like preview_text, send_window_hours, or archive_visibility, which remain undocumented in both schema and description.

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 'Create a newsletter draft for an audience and sender identity,' specifying verb, resource, and scope. It distinguishes from sibling tools like shipmail_update_newsletter or shipmail_schedule_newsletter by emphasizing draft creation and the need for preflight before scheduling.

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 guidance on when to use this tool: it says to prefer blocks for body content and requires at least one of blocks, body_html, or body_text. It also mentions post-creation steps (preflight, scheduling), implying alternatives like shipmail_update_newsletter for editing or shipmail_preview_newsletter for previewing.

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