List Gmail accounts

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

Annotations already declare readOnlyHint, idempotentHint, and destructiveHint, but the description adds valuable behavioral detail: tokens are never exposed, output is one line per account, the no-accounts case is handled, and errors occur only if the local accounts file is unreadable or corrupt.

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 front-loaded with the core purpose, then organized into short labeled sections for args, returns, examples, and errors. Every section adds useful information without excessive wording.

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 zero-parameter read-only tool with no output schema, the description fully covers what the agent needs: invocation, return content, empty-result behavior, and error conditions. Nothing essential is missing.

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?

There are zero parameters and the schema fully documents that with an empty properties object. The description reinforces this with 'Args: none' and a literal '{}' example, adding confirmation even though there is no parameter meaning to elaborate.

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 uses a specific verb and resource: 'List every stored Gmail account,' followed by the exact fields returned. This clearly distinguishes it from sibling tools like gmail_list_labels and account-mutation tools such as gmail_add_account and gmail_remove_account.

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 intended use is clear: call this when you need to enumerate stored accounts and their metadata. It does not explicitly name alternatives or exclusion criteria, but no other sibling provides account listing, so the context is sufficient.

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