mail_create_reply_draft

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

The description discloses important behavioral traits beyond the annotations: the draft is unsent, Graph derives recipients/headers, no sends are possible, and source versions are rechecked but not atomically locked. There is no contradiction with the readOnlyHint or destructiveHint 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 concise, with two focused sentences that convey the core behavior and important limitations without redundancy or unnecessary detail.

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?

The description covers the main operational context—draft creation, derived recipients, no send capability, and concurrency semantics. It does not mention return values or success indicators, but this is partially mitigated by the absence of an output schema and the clarity of the intended side effect.

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?

The input schema is self-explanatory at a structural level, but the description provides no parameter-specific semantics. In particular, requestId and accountId are not explained, and the relationship between messageId and the source message is only implied by the phrase 'from the source.'

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 ('Create an UNSENT reply/reply-all') and identifies the underlying Graph operations, distinguishing it from a generic draft tool. It also explicitly notes that sends are unavailable, which clarifies the intended scope.

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 explains key usage constraints: recipients and headers are derived by Graph, arbitrary overrides and sends are unavailable, and source versions are rechecked rather than locked. It does not explicitly name the alternative generic draft tool, but the constraints make the appropriate use case clear.

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