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

Annotations already declare readOnlyHint=true, idempotentHint=true, and destructiveHint=false, so the safety profile is fully covered. The description adds minimal behavioral context beyond this, such as 'one exact draft' implying a single-resource getter, but no additional side-effect or error behavior is disclosed. Since it does not contradict annotations and adds a small amount of context, a 3 is appropriate.

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 description is two sentences with zero filler: it states the core purpose first, then the critical constraint. All information is front-loaded and every word earns its place, making it highly scannable for an agent.

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 simple getter tool with rich annotations and complete schema coverage, the description is nearly sufficient. It does not explicitly state the return format or error behavior, but the presence of annotations and the tool's straightforward pattern make these gaps minor. An agent can confidently call this tool with the provided ID and account context.

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%, so the schema fully documents both draft_id and account_id, including the instruction that draft_id must come from email_list_drafts/email_create_draft and the account selection logic. The description repeats the draft_id source constraint but adds no new information beyond the schema, fitting the baseline of 3 when schema does the heavy lifting.

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 'Get one exact draft' uses a specific verb and resource, clearly distinguishing it from sibling tools like email_list_drafts (which lists drafts) and email_get_thread (which retrieves a thread). It also adds a precise scoping constraint by stating the draft_id source and excluding subject/email_id, making its unique purpose unambiguous.

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 description explicitly instructs that draft_id must come from email_list_drafts or email_create_draft and never from subject/email_id, which is a strong usage rule that prevents common misidentification. However, it does not explicitly contrast with alternatives like email_get_thread or email_read_message, though the source constraint implicitly routes the agent to the correct sibling for listing drafts.

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