bulk_add_labels

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

In the absence of annotations, the description carries the burden of disclosing side effects. It clearly states that existing mailbox assignments are preserved, which is a key behavioral trait for a mutation tool. It does not cover error handling or reversibility, but the central side effect is communicated.

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, well-structured sentence of 17 words. It leads with the action, states the object, and adds a meaningful qualifier without any filler 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?

The description covers the core behavior and the key side effect, but for a bulk mutation tool with no output schema and no annotations, it lacks details about partial failures, atomicity, or return values. The schema documents limits (max 100 emails, max 50 labels), but the description itself is not fully self-contained for the entire operational context.

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?

With 100% schema coverage, the baseline is 3. The description adds value by explicitly stating 'preserving their other mailbox assignments,' which clarifies the semantics of both parameters: emailIds receive additions without removal, and mailboxIds are additive rather than replacement. This goes beyond the schema's terse field descriptions.

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 adds labels to multiple emails at once, using a specific verb and resource. The phrase 'while preserving their other mailbox assignments' adds crucial scope and distinguishes it from a simple label-replacement tool, as well as from the single-email 'add_labels' sibling.

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 the intended use case for bulk labeling of multiple emails ('at once') and clarifies the additive nature ('preserving'). However, it does not explicitly name alternatives like 'add_labels' for single emails or state when not to use this tool, so it falls short of full guidance.

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