Star / Unstar Email

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

The description says 'toggle' but annotations indicate idempotentHint=true, creating a contradiction: toggling implies non-idempotent flip while setting a boolean is idempotent. This misleads about actual behavior. Beyond that, no side effects or permissions are disclosed.

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, no wasted words. The first sentence states the action, the second adds critical usage detail. Perfectly 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?

For a simple mutation tool, the description covers the main behavior and a key usage note. However, the toggle ambiguity and lack of mention about return value or required permissions (though output schema exists) leave some gaps.

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?

The description adds value by stating the default for isStarred and the strong recommendation for sourceFolder. Although emailId is not described, the schema coverage is 50% and the description compensates with practical context.

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 'Toggle the starred (flagged) status of an email' which is a specific verb-resource pair. It distinguishes from siblings like bulk_star by focusing on single email.

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 a specific guideline about passing sourceFolder when the UID came from a folder other than INBOX. However, it does not explicitly tell when to use this tool over alternatives like bulk_star or mark_email_read, leaving usage context implied.

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