Add Label to Emails

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

Annotations show readOnlyHint=false, idempotentHint=false, destructiveHint=false, indicating a non-destructive mutation. The description confirms by stating 'Each email remains in its original folder and also appears in Labels/{label}', which aligns with and adds detail to the annotations. No contradictions.

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 sentences, each serving a purpose: first defines action and effect, second provides usage guidance and a note about progress. Concise and front-loaded.

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?

Given the presence of an output schema and the clear explanation of behavior, sibling differentiation, and large-batch notifications, the description is complete for this tool's complexity.

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 75% (3 of 4 parameters described). The description adds the label format detail ('Labels/{label}') beyond the schema's 'Label name without prefix', but the sourceFolder parameter is not mentioned in the description. The baseline is 3 due to high schema coverage, and the description adds only marginal extra meaning.

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 'Add a label to multiple emails' and explicitly distinguishes from the sibling bulk_move_emails by noting when to use that alternative. This provides a specific verb-resource pair with clear differentiation.

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 explicitly tells when to use this tool ('Each email remains in its original folder') versus the alternative bulk_move_emails ('only when messages should leave their source folder'). It also mentions progress notifications for large batches, guiding usage expectations.

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