unlabel_message

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

Annotations already declare idempotent=true, destructive=false, readOnly=false, so the safety profile is covered. The description adds a genuinely non-obvious behavioral trait: moving changes the message id and the new id is returned, which an agent cannot get from annotations. It stops short of covering failure modes (e.g., removing a label that is not 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?

Two tight sentences, zero waste, with the core action first and the id-change caveat second. Every clause carries information an agent needs.

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 two-parameter, low-complexity mutation with no output schema, the description covers the non-obvious return value (new id) and the label effect. Minor gaps remain around idempotent behavior when a label is absent and the lack of messageId documentation.

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 50%: labelIds is richly documented in the schema while messageId has no description anywhere. The description reinforces label semantics with UNREAD/STARRED examples but adds no messageId guidance or id-format detail, so baseline 3 fits.

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 and resource ("Removes labels from a message") and adds concrete examples (UNREAD to mark read, STARRED to unstar) that make the effect unambiguous. It implicitly contrasts with the sibling label_message but never names it, so differentiation relies on the agent inferring the inverse.

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 examples imply the use case (marking read/unstarring), but there is no explicit when-to-use versus alternatives such as label_message, update_message_labels, or unlabel_thread. Folder-move semantics from the schema suggest editing scenarios, yet the description does not route the agent among these overlapping tools.

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