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

Annotations already declare destructiveHint=true, openWorldHint=true and non-idempotent, so the safety profile is known. The description adds genuinely non-structured context: recipient is limited to the connected user, no marketing consent is required, and the send is excluded from results/analytics. It does not mention the confirm dry-run flow that the schema describes.

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 tight sentences, front-loaded with the action and audience, then the two exceptions an agent most needs (no consent, excluded from results). No 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?

For a write tool with annotations covering the risk profile and no output schema, the description supplies audience scoping, consent exemption, and analytics exclusion. The only meaningful gap is that the confirm-based preview behavior is left entirely to the schema.

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%, and the schema already explains confirm's dry-run behavior, variant's A/B meaning, and campaignId's provenance. The description contributes no additional parameter meaning, 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 and resource ('Emails the saved newsletter') and pins down the scope ('to you (the person connected) only, through the workspace's own email'), which separates it from schedule_newsletter or a real send. It never names the adjacent siblings (preview_newsletter, send_test_email), so the differentiation is inferred rather than explicit.

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?

There is no explicit when-to-use or when-not-to-use clause and no named alternative such as preview_newsletter. The '[TEST]' framing and 'never counts in results' only imply the natural use case (rehearsing a newsletter before scheduling), so guidance is present but left to inference.

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