Inbound Email MCP Server

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

Annotations indicate the tool is not read-only, idempotent, or destructive, which the description does not contradict. The description adds behavioral context by explaining the three retry modes (specific endpoint, specific delivery, or all endpoints), which goes beyond annotations. However, it lacks details on side effects, error handling, or rate limits that would enhance transparency.

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, efficient sentence that front-loads the core action ('retry delivery') and lists the three retry options concisely. There is no wasted text, and every part contributes to understanding the tool's functionality.

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 moderate complexity (3 parameters, no output schema) and rich annotations, the description is adequate but incomplete. It covers the purpose and retry modes but lacks details on prerequisites (e.g., email must have failed delivery), expected outcomes, or error conditions, which would be helpful for an agent to use it 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?

Schema description coverage is 100%, so the schema fully documents parameters. The description adds minimal semantics by mentioning the three retry modes, which align with parameters but do not provide additional syntax or format details. This meets the baseline for high schema coverage without significant added value.

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 ('retry delivery') and resource ('received email'), distinguishing it from sibling tools like 'send_email' or 'reply_email' which involve creating new emails rather than retrying existing ones. It specifies the scope of retry operations (specific endpoint, specific failed delivery, or all endpoints), making the purpose unambiguous.

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 implicitly suggests usage when an email delivery has failed and needs to be retried, but it does not explicitly state when to use this tool versus alternatives like 'send_email' for new emails or 'reply_email' for responses. It provides context on retry options but lacks explicit exclusions or comparisons with sibling tools.

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