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

Annotations already flag destructiveHint=true, idempotentHint=true, and readOnlyHint=false, so the safety profile is established. The description adds substantial context beyond that: no undo, deletion limited to drafts in scoped accounts, that nothing else in the mailbox can be deleted, the Pro prerequisite, and the side effect that every reply costs a draft even on error.

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?

The opening sentence delivers the core action and permanence immediately, and every following sentence adds a distinct, useful constraint or relationship. Despite the length, there is no filler; each clause earns its place by clarifying identification, scope, side effects, or prerequisites.

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?

An output schema exists, so return values need not be explained. The description covers invocation paths, scoping limits, destructive permanence, cross-tool context, side effects, and the Pro requirement, leaving an agent with everything needed to call it responsibly.

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 0%, so the description must carry parameter meaning. It names all four parameters and gives the key selection rule that draft_id comes from list_drafts or the match_* fields must resolve to exactly one draft, which is enough to invoke the tool correctly. It leaves some gaps, such as exact matching behavior per match_* field and explicit mutual exclusivity, so it is strong but not complete.

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 verb and resource (delete one draft) and immediately adds the permanence scope, distinguishing it from sibling read/list tools like list_drafts and show_draft. An agent can tell exactly what this tool does 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?

It gives explicit identification paths (draft_id from list_drafts, or the match_* parameters that must resolve to exactly one draft) and names related tools (list_drafts, update_draft) with the conditions that connect them. It also explains the cleanup use case after a failed reply, so both when and why to call it are clear.

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