SandMail — Disposable Email API for AI Agents

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

With no annotations, the description carries full burden and effectively discloses key behavioral traits: it blocks execution until an email arrives or timeout occurs, extracts codes automatically, and specifies a timeout range (implied by schema). It doesn't detail error handling or exact extraction logic, but covers core behavior well.

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?

Two sentences with zero waste: the first states the core functionality and behavior, the second provides usage context. It's front-loaded with essential information and appropriately sized for the tool's complexity.

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 no annotations and no output schema, the description is mostly complete for this tool's complexity—it explains blocking, automation, and use case. However, it lacks details on output format (e.g., what the extracted code looks like) and potential failure modes, leaving minor gaps.

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 schema already documents both parameters fully. The description adds no additional parameter semantics beyond what the schema provides, such as format examples or edge cases, meeting the baseline for high schema coverage.

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 with specific verbs ('wait for', 'extract') and resources ('email', 'OTP/verification code'), distinguishing it from siblings like get_otp or wait_for_email by emphasizing automation and blocking behavior.

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 explicitly states when to use this tool ('most useful tool for account verification flows') and implies alternatives by mentioning siblings like get_otp (which likely doesn't block) or wait_for_email (which might not extract codes), providing clear context for selection.

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