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

Annotations already declare the safety profile (destructiveHint=true, idempotentHint=true, readOnlyHint=false), so the bar is lower. The parenthetical "archived conversations leave the main inbox" adds genuine semantic value beyond the annotations by explaining what archiving actually does.

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?

Two compact sentences with the actions front-loaded and no filler. The "or ... or ..." construction with an inserted parenthetical is slightly clunky but still efficient.

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?

A three-parameter mutation with full schema coverage and safety annotations; the description covers all three operations plus usage timing, which is nearly everything an agent needs. No output schema exists, so return values need not be explained, though permission/prerequisite details are absent.

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%, and the description largely restates the schema's own boolean semantics ("read or unread", "archive it ... or move it back", "after handling a reply"). With the schema already doing the heavy lifting, the 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?

States a specific verb (update) and resource (conversation) and enumerates the three state changes it can perform: read/unread, archive, and unarchive. It is distinguishable from get_conversation and send_conversation_message, though it never names a sibling to sharpen the boundary.

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?

"Use after handling a reply" gives a clear situational trigger for invoking the tool. It offers no explicit exclusions or named alternatives, so it falls short of a full when/when-not rubric.

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