Read the full contents of a message

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

No annotations are present, so the description must disclose behavioral traits itself. It clearly states this is a read operation returning the full body and attachment list, which implies non-destructive behavior. It does not explicitly confirm no side effects or mention permissions, but the verb 'Read' and resource scope make the safety profile evident.

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 wasted words. The action and resource come first, followed by usage conditions and an explicit alternative. 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 tool with two required parameters and no output schema, the description provides sufficient context: what it reads, what it returns, and when to use it instead of the key sibling. No critical operational detail 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?

Schema coverage is 100%, with both 'address' and 'message_id' described meaningfully. The message_id parameter even notes it comes from wait_for_email or list_messages, which is helpful. The description body adds no extra parameter semantics, but the schema already carries the full load, so baseline 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?

The description states a specific verb ('Read') and resource ('a message's full body and attachment list'), making the tool's purpose unambiguous. It also distinguishes itself from the sibling get_verification_code by addressing the case where code extraction fails. The title reinforces the same purpose.

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 gives explicit usage conditions: use when the user wants to see an email's actual content, or when get_verification_code could not find a code. It names an alternative tool and specifies the scenario that selects this one, leaving no ambiguity about when to invoke read_message.

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