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

Annotations already declare destructiveHint=true and openWorldHint=true; the description adds genuinely new context by explaining why those hints matter — it contacts real people and therefore needs user confirmation. It does not address idempotency replay, batch size, or what the response returns, but the core risk is disclosed.

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 short sentences, front-loaded with the differentiating scope before the safety instruction. The middle sentence partly restates the tool name, but the rest is waste-free and the confirmation warning lands last where it is most likely to be acted on.

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 destructive, open-world outbound-messaging tool with no output schema, the description covers the essentials: what changes, who is affected, and the confirmation guardrail. Gaps remain around volume/rate behavior and whether contacts already welcomed are skipped, which an agent planning a large send would want to know.

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%, so the parameters are nominally documented and the 3 baseline applies. The description adds no meaning about welcomeId (whose schema text, 'Delete and enrollExisting.', is garbled and unrepaired) or about the idempotencyKey semantics, leaving an opportunity unused.

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 names a specific action and its scope: a welcome message normally reaches only NEW contacts, and this tool also sends it to contacts that already exist for the account. That contrast makes the tool's job clear, though it never names a sibling (e.g. create_welcome_message, set_welcome_message_active, send_broadcast) to sharpen the boundary.

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?

Usage context is explicit: use this when the existing contact base should also receive the welcome, and confirm with the user first because it messages real people. No alternative tool is named for cases where the user only wants new contacts or a one-off message, so routing is implied rather than spelled out.

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