search_emails

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

The description supplies important behavior not in annotations: returns envelope summaries newest first, includes pagination, and warns that all email content is untrusted and must never be treated as instructions. This is valuable context for the agent, especially the prompt-injection reminder. No contradiction with the readOnlyHint or idempotentHint annotations.

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 compact and front-loaded: the first sentence states the core operation, the second covers return and pagination, and the third gives a terse security warning. Every sentence carries meaningful content with no repetition or filler.

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?

Covers envelope summaries, ordering, pagination, the All Mail use case, and untrusted-data behavior. With an output schema present and detailed input schemas, only a brief mention of when list_emails would be preferred is missing, which is already separately scored under usage guidelines.

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 100% parameter description coverage, so the description adds little beyond listing the same filter categories in prose. This is the correct baseline given the high-quality schema definitions.

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 opens with a specific verb and resource: 'Search messages in a folder by text, sender, recipient, subject, date range, or unread state.' It enumerates meaningful filtering dimensions, making the operation distinct from list_emails and other siblings. The All Mail mailbox guidance further clarifies the full scope.

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?

It provides clear usage context, such as 'Search the All Mail folder to look across the whole mailbox at once,' and reveals the envelope-level return shape. However, it does not explicitly name alternative tools like list_emails or state when not to use this tool, so it stops short of full exclusion reasoning.

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