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

Annotations only cover the safety triad; the description goes far beyond by disclosing unsubscribe-bypass asymmetry, the 75-recipient Marketing Suite threshold, SMS segment billing, in-app notification gating, the per-call confirmation default and its toggle, and the required Cotlet API key scope.

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?

Purpose is front-loaded and the operational caveats earn their place, but the channel enumeration ('by email, SMS or in-app message' / 'by email, SMS or in-app') is stated twice, and the sentence order mixes capability, constraints, and safety prompts without tight grouping.

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 mutation tool with no output schema, the description supplies everything needed to call safely: recipient scoping, channel limits, cost implications, delivery gating, confirmation defaults, and auth requirements. Nothing material is missing.

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 body, channel, subject, and customer_ids are already documented. The description reinforces the channel choice and the one-vs-many customer behavior but adds no format or syntax detail beyond the schema's own descriptions; 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 (send/message) and resource (customers) plus all three channels, and locates it precisely ('from Home > Inbox'). No sibling delivers messages in the Momence family, so an agent can immediately tell this apart from book_customer, cancel_booking, etc.

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 clear decision-relevant conditions: multi-recipient messages skip unsubscribed customers while one-to-one does not, 75+ email recipients require the Marketing Suite, and in-app only reaches users with notifications enabled. It lacks a direct sibling alternative to route to, but the situational constraints are well articulated.

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