search-emails

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

Annotations already declare readOnlyHint=true, and the description reinforces this with 'read-only' and explains fallback behavior for Outlook.com accounts. It adds context on paging and defaults but does not cover all edge cases (e.g., rate limits). The bar is lowered due to annotations, and the description adds meaningful behavioral context.

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 approximately 150 words and well-structured, starting with the main purpose then detailing each mode. While it is lengthy, the complexity of six modes justifies the length. It is front-loaded and every sentence adds value, earning a solid 4.

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?

Given the tool's 20 parameters and no output schema, the description thoroughly explains return values ('Returns paged messages with id/subject/from/receivedDateTime/preview by default; use outputVerbosity to expand') and covers all six modes. It is complete for a read-only search tool, though it lacks error handling details.

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%, so baseline is 3. The description adds value by explaining how parameters combine into six modes, clarifying relationships (e.g., deltaMode and deltaToken) and providing practical usage examples. This goes beyond the schema's individual parameter descriptions.

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 clearly states the tool's purpose: 'Search, list, delta-sync, or thread-group emails — six modes selected by parameters (read-only).' It uses specific verbs and resources and distinguishes itself from sibling tools like read-email and update-email by covering multiple modes.

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 explicitly details when to use each mode by parameter combinations, e.g., 'With no params: lists recent emails... With query/from/to/subject/date filters: full search...' It also provides guidance on limitations for Outlook.com accounts, helping the agent choose the right mode.

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