Check if an email address is deliverable. Get a structured result indicating whether it is valid, invalid, or risky to improve your email list quality.
Verify an email address and return a structured deliverability result.
| Name | Required | Description | Default |
|---|---|---|---|
| address | Yes | Email address to verify |
| Name | Required | Description | Default |
|---|---|---|---|
| Yes | |||
| reason | Yes | ||
| status | Yes |
Changes observed during successful MCP inspections.
v0.1.0Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
No annotations are provided, so the description carries the full burden of disclosing behavior. It states that a structured result is returned, but does not mention whether verification involves network calls, SMTP checks, sending a test email, or any side effects or limitations. This is a meaningful gap for a verification tool.
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 a single, focused sentence that names the action and the outcome without any filler. It is front-loaded and easy to parse.
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 simple single-parameter interface and the presence of an output schema, the description is nearly complete for invocation purposes. The main shortfall is the lack of behavioral context around how verification is performed, but this does not prevent an agent from calling the tool correctly.
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 schema fully documents the only parameter, 'address', with a clear description. The tool description adds no additional nuance about formatting, normalization, or edge cases, but the schema coverage is 100%, so the baseline 3 is appropriate.
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 identifies the action (Verify) and the resource (an email address), and specifies that the output is a structured deliverability result. This is unambiguous and sufficiently distinguishes the tool for its intended use.
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 a clear use case: when an agent needs to validate an email address and obtain a deliverability verdict. There are no sibling tools or alternative options mentioned, so no exclusionary guidance is necessary. It lacks explicit 'when not to use' guidance but the context is reasonably clear.
Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.