Modify email labels

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

With no annotations provided, the description carries the full burden. It states that labels are added or removed but does not disclose potential side effects, such as whether existing labels are preserved, whether the operation is reversible, or what the return value is. The examples map to label names but do not explain underlying behavior.

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?

The description is a single, front-loaded sentence. It states the core action first and appends parenthetical examples for clarity. Every word earns its place, with no fluff or redundancy.

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 simple modification tool with 4 parameters and no output schema, the description adequately conveys the basic action and examples. However, it lacks details about prerequisites (e.g., message must exist), side effects, or return behavior, leaving some gaps for a tool with no annotation support.

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 is 3. The description adds minimal value beyond the schema; the examples of mark read/unread and star/archive provide user-friendly context but largely overlap with the schema's own examples of STARRED, INBOX, TRASH, and UNREAD.

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 clearly states the tool's purpose with a specific action ('Add or remove labels') and resource ('on a message'). It provides concrete examples (mark read/unread, star, archive) and distinguishes it from sibling tools like send, list, and get.

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 when to use the tool (when label modification is needed) and gives example use cases, but it does not explicitly state when not to use it or mention alternatives. Since there is no direct sibling for label modification, this is acceptable but not fully explicit.

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