gmail_reply_to_thread

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

Describes key behavioral traits: creates a real Gmail draft, opens an interactive composer UI, recipient default logic, and a specific error condition. It also advises on response brevity due to the UI. With no annotations provided, the description carries the full burden and does so well.

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 paragraph structure is concise and front-loaded with the purpose. Every sentence adds value—no filler. The description efficiently conveys all necessary information in about 120 words.

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?

Covers the core use case, edge cases, and behavioral expectations. While it doesn't detail output (output schema exists) or all parameters, it provides enough context for an AI agent to select and invoke the tool correctly given the complexity and sibling tools.

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?

Adds meaning for to, cc, bcc, and body (e.g., default behavior for 'to', explicit control). However, subject, user_id, thread_id, and attachments are not explained in the description. Given 0% schema description coverage, the description compensates partially but not fully for all 8 parameters.

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?

Explicitly states 'Create a reply draft on an existing Gmail thread' and distinguishes itself from composing reply text in chat. The description is specific about the resource (Gmail thread) and the action (create reply draft), making its purpose unmistakable.

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?

Provides clear when-to-use instructions ('ALWAYS use this tool instead of composing reply text in chat') and covers an edge case (when 'to' must be explicitly passed if all messages are from the user). However, it does not explicitly compare to other sibling Gmail reply tools like gmail_inbox.reply.

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