bulk_update_labels

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

The annotations set destructiveHint to false, which aligns with the non-destructive nature of adding/removing labels. The description mentions the operation but does not detail behavioral aspects like idempotency, rate limits, or what happens with duplicate operations. With annotations covering the safety profile, a 3 is appropriate.

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 three sentences with no filler. Each sentence conveys essential information: purpose, when to use, and parameter constraint. It is front-loaded with the main action.

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 tool has 7 parameters, a nested object (match), and no output schema, the description adequately explains the two modes of operation and the maxBatchSize safeguard. It is complete enough for correct invocation, though more detail on return values or error cases could be added.

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 86%, so most parameters are already described. The description adds value by explaining the XOR relationship between emailIds and match+folder, noting default maxBatchSize (500), and giving an example for labelsToAdd. This improves understanding beyond the schema.

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 function: 'Add or remove Proton labels on multiple messages simultaneously.' It specifies the resource (labels) and action (add/remove), and distinguishes it from sibling tools like 'bulk_move'.

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 provides explicit guidance: 'Use when the same label change should apply to several messages.' It also explains the XOR constraint between emailIds and match+folder, helping the agent choose parameters. However, it does not explicitly advise against using for single messages.

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