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

Annotations already declare readOnlyHint=false, destructiveHint=false and idempotentHint=true, so the safety profile is largely covered. The description adds a real behavioral detail – the message must be the customer-approved text sent to an owned conversation – but omits the required confirmation gate and what happens on failure, leaving meaningful gaps.

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?

A single eleven-word sentence with the verb front-loaded and no filler, which is efficient. However, given a five-parameter mutation with a confirmation gate, this brevity reads as under-specification rather than disciplined conciseness.

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 no output schema, five parameters and zero schema documentation, the description is far too thin. The confirmation requirement, idempotency behavior, attachment handling, and error/return expectations are all absent, so an agent cannot call it correctly without inference.

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 0% across five parameters, so the description carries the full burden and delivers very little. 'One owned conversation' loosely implies conversationId ownership and 'exact customer-approved message' hints at verbatim body content, but clientMessageId (idempotency), attachmentIds, and the confirmed const-true confirmation gate are never explained.

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') and resource ('message') scoped to a single owned conversation, which clearly separates it from the read-only sibling support_messages_list. The phrase 'exact customer-approved message' is slightly opaque but the core action is unambiguous.

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?

No when-to-use guidance, no exclusions, and no reference to alternatives such as support_messages_list or support_conversation_close. The only usage constraint offered is 'one owned conversation', which is a scoping fact rather than routing guidance.

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