Read an email

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

Annotations already declare readOnlyHint=true, idempotentHint=true, and destructiveHint=false, so the description does not need to repeat the safety profile. The description adds the detail-level options, which are useful, but it does not disclose behavior around missing IDs or failure handling. This is acceptable given the strong annotation coverage.

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 one concise sentence that front-loads the core action and resource, then packs the detail-level variants compactly. There is no filler or redundant explanation.

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 read operation with strong annotations and well-described parameters, the description is nearly complete. It conveys the resource, ID source, and detail levels, though it does not specify the exact return structure for each view. This is a minor gap for such a straightforward retrieval tool.

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 already provides full descriptions for both parameters, including the enum, default, and payload-size explanation for 'view'. The description repeats the view concept but adds little meaning beyond the schema. Baseline 3 is appropriate because schema coverage is high.

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 ('Read') and resource ('one email by envelope ID'), and specifies the available detail levels. It clearly distinguishes the tool from sibling tools like schedule_email and mailbox_delete, which involve different actions.

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 main description does not name alternatives, but the parameter description for 'id' provides clear context: this tool is used when an envelope ID has been obtained from search, recent, or thread tools. This gives sufficient usage context, though it does not explicitly state when not to use the tool.

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