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

Annotations only declare readOnlyHint=false and destructiveHint=false; the description adds meaningful context beyond that by stating the write-scope requirement and clarifying that this records an off-platform send rather than performing one. It stops short of describing downstream effects, such as whether the approval queue item is cleared or a status/timestamp is recorded, which matters for a state-changing call.

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, each carrying distinct information: what it does and for which channels, the routing exception, and the auth requirement. The core action is front-loaded and there is no redundant restatement of the tool name or schema.

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 one-parameter mutation with no output schema, the definition covers trigger conditions, the principal alternative, and authorization. The main remaining gap is post-call behavior — what state the draft or approval item ends up in and what the response confirms — which an agent would want when chaining calls.

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 coverage is 100%, and the schema's id description already explains the approval-item-ID vs message-ID distinction in detail. The description adds nothing about the identifier or its format, so the baseline 3 applies rather than any credit for extra semantic guidance.

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 ('mark ... as sent') with a precisely scoped resource: pending manual-channel drafts limited to tiktok or instagram cold first-touch. The parenthetical scope and the explicit pointer to approve_message let an agent distinguish this from the other send-adjacent siblings without opening any schema.

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 an explicit when-to-use condition (draft was sent outside the platform) and an explicit when-not with the alternative named (API-sendable drafts must use approve_message). It also states the prerequisite of write scope, so an agent has routing rules and an authorization gate in one place.

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