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

Annotations already declare readOnlyHint=true, destructiveHint=false, and openWorldHint=false, so the safety profile is established. The description adds that it never sends and that a null reply means nothing was saved, but 'never sends' largely repeats the annotations and return semantics are partly covered by the output schema. The added value is modest.

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 usage trigger and key safety/return facts. No filler; even the null-return note is compact and purposeful.

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?

Annotations, an output schema, and full parameter description coverage make this definition nearly self-sufficient. The remaining gap is that the description does not say whether card_id, draft_id, or both should be supplied, though the schema sources make this inferable.

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%, with card_id documented as 'From a reply card' and draft_id as 'From reply_prepare.' The description does not mention either parameter or explain how they relate, so it adds no meaning beyond the schema baseline.

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 states a specific check for a specific resource: see whether a reply 'went out.' It also gives the triggering condition, so the agent can distinguish this from sending. It does not explicitly differentiate from any sibling, but none of the listed siblings are direct alternatives.

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?

It names the exact situation that selects this tool: 'when a reply was not confirmed.' That is clear context for use. It does not discuss when not to use it or name alternatives, but the scope is narrow enough that this is not a major gap.

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