mark_unread

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

There are no annotations, so the description must carry the full behavioral disclosure burden. It states that the tool changes a message to unread, but does not mention idempotency, whether the message must already be read, any permissions, or expected response behavior. The description largely restates the tool name rather than adding behavioral context.

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 terse sentence with no filler and the action is front-loaded. It is concise, though slightly under-sized relative to the three-parameter schema and the need for sibling differentiation.

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 mutation tool with no annotations, no output schema, and no parameter explanation, the description is incomplete. It does not distinguish this from related batch/read-state tools, nor does it clarify the optional parameters. An agent would need external knowledge to use it confidently.

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 names no parameters. It does not explain the roles of message_id, mailbox, or include_raw, leaving non-obvious fields like include_raw completely unexplained. The phrase 'a message' weakly implies message_id, but the description adds no real parameter meaning.

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 clear verb-resource pair: 'Mark a message as unread.' It identifies the target entity and the state change, and it is not a tautology. It does not explicitly differentiate from siblings like batch_mark_unread, but the singular 'a message' provides reasonable distinction.

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?

No guidance is given about when to use this tool versus mark_read, archive_message, flag_message, or batch_mark_unread. The description simply states the action without conditions, exclusions, or alternatives. Given the large sibling set, this is a notable gap.

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