Mark messages in bulk

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

Annotations already provide readOnlyHint=false, destructiveHint=false, and idempotentHint=true. The description adds minimal behavioral context beyond the bulk nature, and no contradiction with annotations is present.

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?

A single, front-loaded sentence that states purpose and cost benefit with zero wasted words. It is appropriately concise.

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 rich schema (5 params, 80% described) and annotations, the description is sufficiently complete for a simple bulk operation. It could mention dry_run or uidvalidity safety, but these are adequately captured in structured fields.

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 80%, so the schema carries most parameter semantics. The description only reinforces action values (read/unread/starred) without adding new meaning beyond the enum.

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 tool marks many messages read/unread/starred in one pass, using a specific verb and resource. It distinguishes from per-message operations by highlighting cost efficiency, but doesn't explicitly name the sibling 'mark' tool.

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 phrase 'Far cheaper than one call per message' implies use for bulk marking and provides clear context. However, it lacks explicit exclusion guidance or a named alternative for single-message marking.

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