message_create

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

With no annotations available, the description carries full responsibility for behavioral disclosure. It mentions the need for credentials and the IMAP/Nodemailer format, but it does not describe side effects (e.g., whether the message is actually sent or only stored), return values, or potential constraints. The ambiguous 'Create/append' leaves room for misinterpretation.

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, short sentence that is front-loaded with the primary verb ('Create/append') and resource. It is efficient and avoids redundancy with the schema. However, it is arguably too sparse given the tool's complexity, but the schema compensates for this.

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 13-parameter create tool with no output schema and no annotations, the description is notably incomplete. It does not explain what 'append' means operationally (e.g., where the message goes, whether it is sent), what the return value looks like, or how this tool relates to other message/email tools. The description alone would leave a user uncertain about the tool's real-world 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 provides 100% coverage with descriptions for all 13 parameters, so the baseline of 3 is appropriate. The description adds no additional semantic meaning beyond what the schema already offers, such as clarifying the relationship between alias_username/alias_password and the message content.

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 uses a specific verb ('Create/append') and resource ('a message for an alias'), which clearly conveys the core action. It also hints at the technical context ('IMAP, Nodemailer format'). However, it does not explicitly distinguish this from sibling tools like email_create or message_update, leaving some ambiguity about when to choose this tool over them.

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 states one prerequisite ('Requires alias credentials') but provides no guidance on when to use this tool versus alternatives. It does not mention scenarios, exclusions, or which sibling tools should be preferred for other message operations (e.g., sending vs. appending).

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