mail_get_message

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

No annotations are provided, so the description must convey behavioral traits. It states 'read', which implies a non-mutating operation, but does not disclose authentication requirements, potential rate limits, error behavior, or that it returns only one message. The body mode does hint at output content, but the description is too terse to fully disclose behavior.

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, efficient sentence that leads with the action and essential qualifiers. It is front-loaded and contains no filler. It could be improved by adding usage context, but as a concise statement of purpose it is well-structured and easy to parse.

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 tool with four parameters, three identifier types, and a body-mode option, the description is too sparse. It does not explain the different locator kinds (Graph ID, immutable ID, internetMessageId) or when to use each, nor does it mention the mailboxScope parameter. Without an output schema, it should at least state that the response includes the requested body or headers, but it only hints with 'body mode'. An agent would need to rely heavily on the schema to understand the full behavior.

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 schema already covers 75% of parameters with descriptions (locator, bodyMode, includeHeaders). The description adds minimal value—it mentions 'explicit body mode' but does not elaborate beyond the schema. Since coverage is high, the baseline of 3 is appropriate; the description does not compensate for the uncovered mailboxScope parameter, but that is not its role given the baseline.

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 is precise: it names the verb 'read', the resource 'one message', and specifies three identifier types plus an explicit body mode. This clearly distinguishes it from sibling tools like mail_search_messages or mail_get_thread, which handle different operations. There is no ambiguity about what the tool accomplishes.

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 no guidance on when to use this tool versus alternatives. It does not mention that it is for retrieving a single message by ID, that it should be used after a search, or that get_thread is for a whole conversation. The schema's locator description hints at IDs from search, but the description itself offers no such context or exclusions.

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