Read an email

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

No annotations are provided, so the description carries the full burden of behavioral disclosure. It does disclose that the message content includes parsed headers, body, and attachment flags, which is useful. However, it does not explicitly state that the operation is read-only, has no side effects, or require any authentication details beyond what is implied by the schema. The description adds some value but lacks deeper behavioral context.

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 a single sentence that is clear and direct, with no superfluous words. It front-loads the core purpose and includes the key details of what will be returned, achieving high conciseness and good structure.

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?

Given the simplicity of this get tool and the 100% schema coverage, the description is mostly complete. It explains the return contents (parsed headers, body, attachment flags), which partially compensates for the lack of an output schema. However, it does not specify the exact structure of the return value, such as field names or formats, and there is no mention of potential errors or edge cases. Still, for a straightforward getter, this is adequate.

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 input schema provides descriptions for both parameters (id: 'Message ID', account: 'Account nickname to use'), giving 100% schema coverage. The tool description does not add any additional meaning beyond what is already in the schema, so the baseline of 3 applies.

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 the tool's function: fetching a single message with parsed headers, body, and attachment flags. The verb 'fetch' and resource 'single message' make the purpose explicit and distinguish it from sibling tools like google_gmail_list (which lists messages) and google_gmail_send.

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 implies when to use this tool (for retrieving one message) but does not explicitly mention alternatives or exclusions. It lacks explicit guidance such as 'Use google_gmail_list to list messages' or 'Do not use for sending.' The usage context is only implicit via the name and the specification of 'single message.'

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