star_email

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

The description adds behavioral context (uses IMAP Flagged flag, so it's a metadata change) beyond the destructiveHint annotation, which is false. It doesn't contradict annotations and gives enough detail for a simple flag toggle, though it doesn't mention idempotency or error 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?

Three sentences, each earning its place: purpose, use case, and batch alternative. Front-loaded with the core action, no 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 two-parameter mutation with no output schema and minimal annotations, the description covers the essential purpose, use case, and alternative. It doesn't mention return values or error conditions, but these are less critical for such a straightforward tool.

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 50% (emailId described, isStarred not). The description's 'Star or unstar' implies the isStarred parameter's purpose but doesn't explicitly map boolean values to actions. It adds some meaning but not enough to fully compensate for the missing schema description.

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 opens with a specific verb and resource: 'Star or unstar a single email using the IMAP Flagged flag.' It clearly differentiates from siblings like batch_email_action (multiple emails) or mark_email_read (different flag).

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?

It provides a clear use case ('bookmark an important message for later follow-up') and explicitly directs users to batch_email_action when flagging multiple emails, giving both a when-to-use and an alternative.

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