list_gmail_labels

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

With no annotations, description carries full burden. It discloses that it lists all labels, splits them by type, and requires readonly scope. It doesn't address pagination or rate limits, but for a simple list operation with output schema present, this is sufficient.

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 fluff. First sentence states purpose, second gives usage context. Every sentence earns its place.

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 list tool with one parameter and an output schema, the description fully covers purpose, usage context, and prerequisites. No additional details needed.

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?

Only one parameter (user_google_email) with 100% schema coverage. Description adds no extra semantics beyond schema; baseline of 3 is appropriate.

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?

Description clearly states it 'list every label in the user's mailbox, split system vs user.' This is a specific verb+resource pair, distinguishing it from sibling tools like manage_gmail_label which modify labels.

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?

Explicitly states use case: 'Use this to discover label IDs before calling modify_gmail_message_labels / batch_modify_gmail_message_labels / manage_gmail_filter — label IDs (not names) are what those tools require.' Also notes required OAuth scope, providing clear guidance on when to apply.

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