Email Mark Unread

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

Annotations already declare readOnlyHint=false, indicating a mutation. The description adds the technical detail 'clear \Seen', which explains the underlying mechanism. However, it does not disclose potential side effects, error conditions, or the requirement for the message to exist in the specified folder. It adds some value but not rich behavioral context beyond what annotations and schema already provide.

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 concise sentence that front-loads the action and result. No wasted words; it is appropriately sized for the tool's simplicity.

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 presence of an output schema (as indicated by context), and annotations covering mutation behavior, the description is sufficient for an agent to call it correctly. It could mention the need to specify a non-default folder, but the schema already covers that. Overall, minimal but complete.

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%, with both folder and message_id having descriptive text in the schema. The description does not add further meaning to the parameters; it only mentions 'message' generically. Since the schema already documents parameters well, a baseline of 3 is appropriate.

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 'Mark a message as unread (clear \Seen)' states a specific verb (mark), a clear resource (a message), and the precise state change (unread). It clearly distinguishes from sibling email_mark_read, which does the opposite. No ambiguity.

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 does not explicitly state when to use this tool versus alternatives like email_mark_read or email_move. It implies the action but does not provide guidance on choosing it over the sibling. The context is clear enough for an agent to infer, but it lacks explicit routing instructions.

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