reply_message

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

With no annotations, the description takes responsibility. It discloses the error behavior for non-text messages and the 'as bot' context, but does not mention success confirmation or any side effects.

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 sentence that gets straight to the point. It could benefit from clearer structure (e.g., separating purpose and constraints), but it is appropriately sized and front-loaded.

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 simplicity, the description covers purpose, limitation, and error condition. It does not describe success outputs, but with no output schema, the omission is acceptable for a basic action tool.

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 coverage is 100%, so the description adds minimal extra value beyond the field descriptions. It reinforces the purpose but does not enhance parameter understanding beyond what the schema provides.

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), the resource (specific message by message_id), and the actor (as bot). It also specifies the limitation to text messages, distinguishing it from send/forward tools among siblings.

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 explicitly states the tool only works for text messages and returns an error for other types, providing clear when-not-to-use guidance. However, it does not explicitly list alternatives or when to prefer this over siblings.

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