create_reply_draft

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

With no annotations, the description carries the full burden of behavioral disclosure. It reveals the return value (pre-filled recipients, quoted body, RE: subject) and implies that no sending occurs by referencing send_draft as a separate step. This is meaningful context, though it does not mention potential side effects or persistence details explicitly. The workflow hint adds transparency.

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 three sentences with no waste. It front-loads the primary action, then describes the return value, then gives the follow-up workflow. Every sentence earns its place and the structure is logical and easy to scan.

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 tool with a single parameter and no output schema, the description is complete. It covers purpose, expected output, and subsequent steps. The sibling tool names further disambiguate the exact reply mode. No additional context is needed for an agent to invoke this correctly.

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% for the single parameter (messageId), which is clearly described as coming from get_emails or search_emails. The tool description adds no extra parameter details beyond the schema, so the baseline of 3 applies – the schema does the heavy lifting and no additional semantics are needed.

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 uses a specific verb ('Create') and resource ('a draft reply to the sender of a message'), clearly distinguishing it from sibling tools like create_reply_all_draft and create_forward_draft. It also specifies key output features (pre-filled recipients, quoted body, RE: subject), leaving no ambiguity about the tool's function.

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 provides clear workflow guidance: 'Use update_draft to modify, then send_draft to send.' It implicitly differentiates from create_reply_all_draft by specifying 'to the sender.' However, it does not explicitly state when NOT to use this tool versus alternatives, so it stops short of a full when/when-not contrast.

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