reply_to_message

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

With no annotations, the description carries the burden and does disclose the important behavioral detail of setting In-Reply-To/References automatically. However, it omits other behavioral aspects such as whether it sends immediately, permissions required, or potential side effects, so it is only partially transparent.

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 a single, concise sentence that conveys the core purpose and the key threading nuance without any filler or repetition. It is well-structured for quick comprehension.

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 tool with three parameters and no output schema, the description covers the main purpose and a critical behavior, but it lacks parameter-level details and any discussion of return values or edge cases. The low annotation coverage makes it 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 33% (message_id is described but html and text are not). The description adds no extra meaning about the html and text parameters, leaving the agent with weak guidance on how to use them or which is preferred.

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 action ('Reply to a message') and the key distinguishing feature ('staying in its thread'), which separates it from siblings like send_message or forward_message. It specifies the resource and the threading behavior explicitly.

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 implies when to use this tool (replying within an existing thread) and mentions the automatic header setting. However, it does not explicitly reference alternatives or state when not to use it, though the thread-staying detail provides clear context.

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