Mark read / unread

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

No annotations are provided, so the description carries the behavioral disclosure burden. It clearly states the core mutation: setting or clearing the \Seen flag. However, it omits any side effects, permission requirements, or failure behavior that would be useful for a mutation tool with no annotation support.

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 one short, front-loaded sentence with no filler. Every word contributes meaning, and the action verb appears first.

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 three-parameter tool with no output schema, the definition is nearly complete. The only notable gap is the lack of explicit when-to-use guidance relative to the sibling tools, but the low complexity and adequate schema coverage keep this from being a major issue.

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 67%, covering uid and folder. The phrase 'Set or clear' effectively explains the undocumented read parameter's two states, compensating for the schema gap. Combined with the default values, an agent has enough parameter understanding to invoke the tool 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 uses a specific verb ('Set or clear') and a specific resource ('\Seen flag on a message'), making the tool's purpose unambiguous. It distinguishes itself from the sibling email tools, which are about sending, replying, listing, or searching rather than changing read state.

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?

There is no guidance about when to use this tool versus the sibling tools, nor any exclusions or prerequisites. The intended usage is only implied by the tool name and title, not explicitly stated.

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