copy-mail-message

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

Annotations already provide readOnlyHint=false and destructiveHint=true, so the safety profile is known. The description adds behavioral context by specifying that it returns a newly created message with a new id, and it clarifies the destination folder format. It does not contradict the annotations, and it provides sufficient detail about the operation's effect and output.

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 well-structured: the first sentence states the core purpose, the tip line expands on the body and return value, and the final sentence routes the user to the sibling tool. No redundant words, front-loaded with key info, and every sentence earns its place.

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 moderate complexity (5 parameters, nested object) and no output schema, the description covers the essential usage: body structure, return value, and alternative. It does not dwell on confirm/includeHeaders/excludeResponse, but those are self-explanatory and documented in the schema. Minor gaps like permission requirements or error cases are not critical for an agent to invoke it correctly.

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 schema covers 80% of parameters with descriptions. The description adds meaningful semantics to the DestinationId parameter by providing concrete examples like 'inbox, archive, junkemail' and clarifying it accepts a well-known name or ID. This goes beyond the schema's generic string type and helps an agent format the request correctly.

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: 'Copy a message to a folder within the user's mailbox.' It identifies the resource (message), the operation (copy), and the destination (folder). It also explicitly differentiates from the sibling tool by stating 'For moving instead of copying, use move-mail-message,' which disambiguates it from similar operations.

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 tells when to use this tool versus alternatives: it copies a message, and for moving, it points to move-mail-message. This explicit guidance helps the agent choose correctly. It also explains the body structure and return value, providing operational context within the same description.

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