Read an email

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

With no annotations provided, the description carries the full behavioral burden. It does disclose that this is a read operation ('Fetch') and usefully clarifies that only attachment flags are returned, not the attachments themselves. However, it doesn't mention body content format (HTML vs plain text), truncation behavior, or error cases for invalid/absent IDs.

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?

A single 12-word sentence with zero waste. The verb and resource are front-loaded, and the result detail is packed efficiently. Every word contributes.

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 read tool, this is nearly complete. With no output schema present, the description helpfully enumerates return components (parsed headers, body, attachment flags), serving the role of return-value documentation. Minor gaps remain around error behavior and body format, but nothing an agent would struggle with for a basic fetch.

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 100% — both 'id' and 'account' are already documented in the schema. The description adds no parameter-level detail beyond the implication that 'id' selects which single message to fetch. This matches the baseline of 3 for high schema coverage.

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 states a specific verb ('Fetch'), a resource ('a single message'), and the expected result ('parsed headers, body and attachment flags'). This distinguishes it from google_gmail_list (multiple messages), google_gmail_get_attachment (attachment content, not the message), and google_gmail_drafts_get (drafts, not messages).

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 usage context is implied: use this when you need to read one email message. However, no explicit routing guidance is given — there's no mention of using google_gmail_get_attachment for actual attachment content or google_gmail_list for browsing messages. Given over 70 siblings, explicit when/when-not guidance would materially help.

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