Reply To Inbox Thread

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

Annotations indicate destructiveHint=true and readOnlyHint=false. The description adds behavioral context beyond annotations, particularly the need for user approval before sending. It does not contradict annotations.

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: the first clearly states the purpose, and the second provides critical usage guidelines. No wasted words, front-loaded with key information.

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?

With an output schema present, return values are covered. The description covers purpose and usage context but lacks guidance on parameter handling. Given the tool's complexity (12 parameters, nested objects), the description is adequate but not complete.

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 only 25%, requiring the description to compensate. However, the description provides no parameter-level details, leaving agents to infer parameter usage from the schema alone. This is insufficient for a tool with 12 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?

The description clearly states the tool's function: 'Reply to a JMAP inbox thread within its mailbox.' It specifies the resource (inbox thread) and verb (reply), distinguishing it from sibling tools like shipmail_reply_to_inbox_message or shipmail_reply_to_thread.

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 explicit usage guidance: 'Use the mailbox and thread IDs returned by inbox tools, and only send after the user approves the exact recipients and content.' This tells the agent when and how to use it, though it does not explicitly mention when not to use it or alternatives.

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