modify_thread_labels

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

With no annotations, the description carries the full behavioral burden. It does disclose non-obvious semantics (that archive and mark-read are expressed as label removal, and that INBOX/UNREAD are special labels), but it says nothing about mutation safety, idempotency, behavior when a label is already present or absent, or what is returned.

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 short sentences, front-loaded with the core action and followed by the highest-value usage idioms. Nothing is wasted and no sentence is redundant.

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 mutation tool with no annotations and no output schema, the definition covers the action and label idioms but omits return values, error behavior, permission requirements, and the source of label ids. An agent could call it, but would be guessing at the outcome and at obtaining valid ids.

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 0%, so the description must compensate: it does explain the roles of add_label_ids versus remove_label_ids and gives concrete label values. However, it never says where label ids come from (e.g. list_labels) or that thread_id identifies the target, leaving real gaps for three undocumented parameters.

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 concrete verb pair and resource: 'Add or remove label ids on a thread.' That is unambiguous, and no sibling tool (get_thread, list_labels, update_draft) could be mistaken for it, though it never explicitly contrasts itself with them.

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?

It supplies concrete recipes that map user intents to parameters ('Archive = remove INBOX', 'Mark read = remove UNREAD'), which effectively tells an agent when to reach for this tool and how to configure it. It stops short of naming alternatives or stating when not to use it.

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