Draft Gmail Message

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

Given the annotations already declare readOnlyHint=false and destructiveHint=false, the bar is lower. The description adds useful context about Send As and reply draft support, but it doesn't disclose whether the tool creates a new draft each time (idempotency), what happens to the draft after creation, or any auth nuances beyond the required parameter. The extra context is helpful but not rich.

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 tightly written sentences pack in the core purpose and key capabilities. Every clause adds value without repetition or filler. The description is front-loaded with the action and resource.

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?

Given the tool's complexity (15 parameters, rich schema, output schema), the description provides a competent high-level overview. It doesn't mention all features like quote_original or include_signature, but those are thoroughly documented in the schema. For an agent, the overview plus schema is sufficient to understand the tool's role and major switchable behaviors.

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 baseline is 3. The description adds high-level meaning by grouping parameters: 'new drafts and reply drafts' (thread_id, in_reply_to, quote_original), 'optional attachments' (attachments), and 'Send As' (from_email/from_name). This helps the agent understand how parameters relate, going beyond the schema's individual descriptions.

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 opens with a specific verb-resource pairing: 'Creates a draft email in the user's Gmail account.' It clearly distinguishes itself from siblings like send_gmail_message and get_gmail_message_content by focusing on drafting. The detail about supporting new and reply drafts adds further precision.

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 clearly conveys when to use this tool: when you want to create a draft rather than send. It also mentions features like reply drafts and Send As, which signal when to use those capabilities. However, it does not explicitly name alternative tools (e.g., send_gmail_message) for the complementary action, so it falls short of a 5.

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