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

Annotations already declare destructiveHint=true, readOnlyHint=false, and idempotentHint=true, so the safety profile is covered. The description adds genuinely new context beyond them: "It was never sent, so nothing reaches anyone" communicates the actual blast radius of the deletion, which the hints do not.

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?

Two short sentences, front-loaded with the action and containing no restatement of the title or schema. Every clause adds either the identifier source or the consequence.

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?

With one required parameter at full schema coverage, annotations covering destruction and idempotency, and an output schema in place, nothing an agent needs in order to call this correctly 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 coverage is 100% and the id property already documents the drf_ prefix, so the baseline is 3. The description goes one step further by naming the two sibling tools that produce a valid id, which the schema does not explain.

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 pairs the specific verb "Delete" with the resource "a draft" and names the identifier it keys on. It is unambiguous against siblings such as list_drafts, draft_sms, and cancel_text, which the agent can rule out 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?

"the user no longer wants" gives a clear triggering condition and "by its id from draft_sms or list_drafts" tells the agent where the id must come from, which is a real prerequisite. It stops short of explicit when-not guidance or naming an alternative for cases like cancelling a scheduled send.

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