get_email

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

Annotations already declare readOnlyHint=true and openWorldHint=true, and the description is consistent with them. It adds useful behavioral context beyond annotations: the returned content includes the body and that overly long content will be truncated. This is exactly the kind of caveat an agent needs before invoking the tool.

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?

One compact sentence that front-loads the core action ('读取单封邮件的完整内容') and adds the key caveat in parentheses. Every element earns its place, and there is no redundant repetition of the tool name or schema fields.

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 two-parameter read-only tool with strong annotations and fully documented schema, the description is sufficiently complete. It covers the main return expectation (full email content including body) and the critical truncation behavior. No output schema exists, so an agent must infer the exact return shape, but the description gives enough for correct invocation.

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%, so the baseline is 3. The description adds value by saying '超长会截断' (long content is truncated), which gives behavioral meaning to maxBodyChars beyond its numeric min/max/default. The id parameter is already well documented in the schema as coming from list_emails or search_emails.

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 ('读取' / read) and resource ('单封邮件的完整内容' / a single email's full content), and clarifies it includes the body. This visually separates it from sibling tools like list_emails and search_emails, which are about finding or listing messages rather than retrieving one full message.

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 'use this when you need the complete content of one email,' but it does not explicitly state when not to use it or name an alternative. The id field's schema hint ('来自 list_emails 或 search_emails') provides indirect routing, but the description itself gives no explicit when-to-use vs. alternatives guidance.

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