Modify message

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

Annotations already declare readOnlyHint=false and destructiveHint=true, so the mutating nature is covered structurally. The description adds genuine value beyond that by warning that a move can change the message id and instructing the agent to switch to moved_uid, a critical operational detail not derivable from annotations.

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 tightly written sentences with zero waste. The purpose is front-loaded in the first sentence, and the second sentence delivers the single most important behavioral caveat (moved_uid). Every word earns its place.

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 9-parameter mutation tool with no output schema, the description covers the main operations and the moved_uid edge case, and the schema fills in the parameter details. However, the return behavior beyond moved_uid (what the response looks like in the general case) is never described, leaving a moderate gap for such a multi-action tool.

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 78%, close to the 80% high-coverage baseline, and most parameters (uid, folder, account, archive, move_to, add_labels, remove_labels) already have descriptions. The description adds only a marginal touch — noting Outlook categories alongside Gmail labels — and does not map operations to specific parameters or clarify the boolean fields, which are self-explanatory.

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 names a clear multi-purpose verb-resource pairing: it modifies a message by marking read/unread, starring, labeling, moving, or archiving. It is easily distinguished from siblings like trash_message (specific deletion) and the read-only fetch/get_message tools, so an agent can tell them apart without inspecting schemas.

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 implies its use case — any message state mutation — which gives clear context, but it never names alternatives or exclusions. With trash_message as a sibling, there is no explicit guidance on when to use this move/label tool versus the dedicated trash tool, leaving some routing to inference.

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