list_emails

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

With no annotations provided, the description carries the full burden for behavioral disclosure. It discloses return content (UIDs and metadata: size, flags, attachment status), but does not state whether the operation is read-only, affects read status, or has pagination/ordering behavior beyond the schema's offset/count. This is adequate but not rich.

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 two concise sentences, front-loaded with the action and resource. Every word earns its place: 'recent' scopes behavior, 'Yahoo Mail folder' identifies the platform, and the return type is summarized without fluff.

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 list tool with fully documented parameters and no output schema, the description is nearly complete. It explains what is returned and a key characteristic ('recent'). It doesn't explicitly mention sorting order or that it does not modify emails, but given the tool's simplicity and schema coverage, this is a minor gap.

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%: every parameter (count, folder, offset) has its own detailed description with defaults. The tool description adds no additional parameter context, so the baseline of 3 applies — the schema does all the heavy lifting.

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 a specific verb and resource: 'List recent emails from a Yahoo Mail folder.' It distinguishes itself from siblings like read_email (individual email), search_emails (query-based search), and list_folders (folder enumeration). The return value overview (UIDs and metadata) further clarifies the tool's purpose.

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 usage for listing emails from a folder but does not explicitly contrast with search_emails or other alternatives. The schema's folder parameter mentions 'Use list_folders,' but the description itself offers no direct guidance on when to choose this tool over siblings. It provides clear context but lacks exclusions.

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