Inxmail MCP

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

No annotations provided, yet description fully discloses critical behaviors: hardbounces auto-add to blocklist, softbounces are temporary, returns paginated HAL+JSON with specific fields, and declares read-only status. Rich behavioral context compensates completely for missing annotations.

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?

Four sentences with zero waste: defines action, explains domain concepts (hard/soft bounces), provides usage guidance with sibling reference, and specifies output format. Front-loaded with core purpose.

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 10 parameters, no output schema, and no annotations, description is remarkably complete: covers domain logic, side effects (blocklist auto-add), pagination format, return fields, and read-only nature. No gaps remain for agent operation.

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 has 100% coverage (baseline 3). Description adds significant semantic value by explaining bounce type distinctions (hard=permanent/blocklist, soft=temporary) and return data structure, enriching understanding of bounceType and pagination parameters beyond schema labels.

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?

Opens with specific verb+resource ('List bounced transactional emails') and immediately distinguishes scope from sibling tool list_relay_bounces by specifying 'transactional emails' vs 'mail relay bounces'.

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?

Provides explicit when-to-use ('investigate delivery issues for event-triggered emails') and explicit alternative ('For mail relay bounces, use list_relay_bounces instead'), creating clear selection criteria against siblings.

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