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

The readOnlyHint is false, and the description goes well beyond that by explaining the exact side effect (moves out of inbox, stays in All Mail), recoverability, the legacy-grant requirement, and that the tool itself will report when the mailbox cannot be changed. This fully discloses the behavioral context an agent needs.

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?

Three sentences, each earning its place: core outcome, usage/confirmation rule, and connection constraint. The most decision-relevant information is front-loaded, and there is no repetition of schema or annotation content.

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 single-message, two-parameter tool with no output schema, the description covers the operation's effect, recoverability, when to use it, the required permission condition, and expected failure mode. Nothing an agent needs to invoke it correctly or decide whether to suggest it is missing.

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 of 3 applies; the schema already documents message_id and account. The description adds a clarifying 'one Gmail message' but does not meaningfully enrich the parameter-level semantics beyond what the schema provides.

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 states a specific verb ('Archive') and resource ('one Gmail message'), then clarifies the exact outcome: it leaves the inbox but stays in All Mail and is fully recoverable. This clearly distinguishes it from deletion, sending, or other Gmail-related sibling tools.

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?

Explicitly says to use it 'only when the user asked for the archive' and to confirm first if it is the agent's own suggestion. It also warns that it only works on legacy modify-grant mailboxes and that current read-only connections cannot change the mailbox, giving clear when-to-use and when-not-to-use guidance.

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