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

Annotations only give destructiveHint=true; the description adds the crucial operational facts that this actually delivers mail (irreversible side effect), that user confirmation is expected, and that gmail.compose scope is required with a reconnect hint for older accounts. This is well beyond what annotations convey.

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 front-loaded sentences, each carrying distinct payload (action, confirmation/alternative, auth requirement). The parentheticals make it slightly dense but nothing is redundant.

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 destructive, no-output-schema tool, the description covers the irreversible nature, the prerequisite scope, the confirmation expectation, and where the parameter comes from. Nothing needed to invoke it 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 both parameters are already documented, including the same 'from list_drafts or get_draft' provenance. The description adds the unedited/AS-IS emphasis but no new syntax or format detail, so it sits at the 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?

States a specific verb+resource ('Send an existing Gmail draft') and immediately scopes it with 'AS-IS, unedited,' which cleanly separates it from update_draft and create_draft among the siblings.

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?

Explicit routing: use this to deliver an existing draft, confirm with the user first, or use update_draft instead if changes are needed. Names both the precondition (draft_id from list_drafts/get_draft) and the alternative tool.

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