reply

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

No annotations are provided, so the description carries the full burden. It reveals little beyond the fact that a reply has attachment and proof rules like send, but does not state what those rules are, whether the action is destructive, how idempotency is handled, or what side effects occur.

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 concise and front-loaded, but it is too sparse for the complexity of the tool. The sentence is efficient yet omits necessary context, making it under-specification rather than effective conciseness.

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 9 parameters, 3 required, no annotations, and no parameter explanation, the description is not complete enough for an agent to use the tool correctly. The presence of an output schema helps, but key behavioral and parameter context is missing.

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 0%, and the description does not compensate by explaining any of the 9 parameters. 'Attachment and proof rules' vaguely references behavior but gives no meaning for required fields like account, message_id, or idempotency_key.

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 replies on a thread, which is a specific verb and resource. However, it does not explicitly distinguish this from send or forward, so it stops short of a 5.

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 phrase 'Reply on a thread' implies the use case, but there is no explicit guidance about when to choose this tool over send or forward. The reference to 'same rules as send' hints at shared behavior but does not provide exclusions or alternatives.

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