SandMail — Disposable Email API for AI Agents

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

With no annotations provided, the description carries the full burden. It discloses key behavioral traits: the inbox is 'temporary disposable' and returns an address that 'can receive emails.' However, it lacks details on permissions, rate limits, or what happens upon expiration (beyond TTL parameter). It doesn't contradict annotations (none exist).

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 sentences, front-loaded with the core purpose and followed by usage guidelines. Every sentence adds value: the first defines the tool, and the second provides critical context for when to use it. Zero waste or redundancy.

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, no output schema, and 3 parameters with full schema coverage, the description is mostly complete. It covers purpose and usage well but lacks behavioral details like response format or error handling. For a creation tool with no output schema, it could benefit from mentioning return value specifics.

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 fully documents all three parameters. The description adds no parameter-specific information beyond what's in the schema, but it implies the tool's purpose relates to the parameters (e.g., TTL for expiration). Baseline 3 is appropriate when schema does 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 the specific action ('Create a temporary disposable email inbox') and the resource ('email address that can receive emails'). It distinguishes from siblings like 'delete_inbox' or 'get_emails' by focusing on creation rather than deletion or retrieval.

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 states when to use this tool: 'Use this when you need to sign up for a service, verify an account, or receive a one-time code.' It provides clear context and distinguishes from alternatives like 'get_otp' or 'wait_for_email' by focusing on inbox creation for initial setup.

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