mark_as_unread

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

With no annotations provided, the description carries the full burden of behavioral disclosure. It only states the basic action and that UIDs are permanent; it does not mention side effects, mutability, permissions, failure behavior, or what happens to the email state beyond marking it unread.

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 compact and front-loaded with the main action, followed by a relevant clarification about UIDs. It contains no filler, though it could include a bit more useful context without becoming bloated.

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 simple two-parameter tool, the description plus schema is minimally adequate for invoking the tool. However, with no annotations and no output schema, it lacks information about expected return values, error conditions, or behavioral consequences, leaving noticeable gaps for an agent.

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 100%, so the baseline is 3. The description adds a small amount of semantic value by noting that UIDs are permanent identifiers, which helps agents understand their stability, but it does not elaborate beyond what the schema already states.

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 ('Mark emails as unread') and the resource (emails), with a specific method (using UIDs). It is not a tautology and is distinguishable from most siblings by the 'unread' intent, though it does not explicitly differentiate itself from the closely related mark_as_read.

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 gives no guidance on when to use this tool versus alternatives like mark_as_read or read_email. It provides no use-case context, prerequisites, or exclusions, so an agent must infer when this tool is appropriate.

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