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

Annotations already flag a destructive, non-idempotent, open-world write; the description adds the substance behind them — delivery reaches every subscriber of the list or segment, consumes sending credit, and cannot be recalled once sent. That is exactly the cost/irreversibility context an agent needs before committing an irreversible action.

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 write/irreversibility warning is front-loaded in the opening clause, followed by prerequisites and the confirmation requirement in a logical order. Every sentence carries non-redundant information; nothing repeats the schema or annotations verbatim.

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 an 8-required-parameter destructive tool with no output schema, the description covers consequences, prerequisite lookups, and the human-confirmation gate. It omits what a successful call returns (campaign uid?) and whether a scheduled campaign can still be modified or cancelled before send_at — the latter is directly relevant given the 'cannot be recalled' warning.

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?

Only 44% of the 9 parameters carry schema descriptions, so the description should compensate more than it does. It adds real provenance for the two UIDs (template_uid, list_uid via sibling tools) and clarifies segment_uid as an optional narrowing of list_uid, but leaves name, subject, from_name, reply_to, and from_email unexplained — those must be inferred from names alone.

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 ('create a campaign ... from an existing template and schedule it for send_at') plus the targeting scope (mailing list or one of its segments). This clearly separates it from read-side siblings like mailblaze_get_campaign and mailblaze_list_campaigns, and from mailblaze_send_transactional_email by emphasizing bulk delivery to a list.

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?

Gives concrete preconditions: a template uid from mailblaze_list_templates and a list uid from mailblaze_list_lists, plus an explicit instruction to confirm list, segment, subject, template and send time with the user first. It stops short of naming when to prefer an alternative route (e.g. transactional email for one-off messages), so it is clear context rather than a full when/when-not map.

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