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

Annotations already declare readOnlyHint=false, destructiveHint=false, idempotentHint=false and openWorldHint=false, so the safety profile is covered. The description usefully adds that nothing is sent (draft-only) and that content is used verbatim with no AI generation or template selection — real behavioral context beyond the annotations. It stops short of noting auth/consent implications or limits on repeated calls.

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?

Three tight sentences, zero filler, with the core action front-loaded and the draft-only/no-AI caveats immediately following. Every sentence carries distinct information.

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 15-parameter mutation tool with a nested audience object and no output schema, the description covers the essential semantics (draft, no send, no AI). It omits any mention of audience targeting or productId, but those are documented thoroughly in the schema, so the gap is minor.

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 93%, so the schema already documents nearly every parameter, including the rich nested audience filters. The description only lists a handful of content fields (subject, title, introduction, sections, button) and adds no syntax or format detail, so baseline 3 is appropriate.

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 ("Saves a new newsletter draft from plain fields") and enumerates the content fields it consumes, so the agent knows exactly what it produces. It also distinguishes its behavior from AI/template-driven siblings ("without AI generation or template selection"), though it never names generate_newsletter explicitly.

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?

"Nothing is sent" and "without AI generation or template selection" imply this is the tool for author-supplied content versus AI drafting, and that a send step is separate. However, no sibling is named and there is no explicit when-to-use/when-not statement or prerequisite guidance, leaving the alternative-selection decision to inference.

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