Inxmail MCP

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

No annotations provided, so description carries full burden. Discloses 'Read-only' status, pagination behavior ('paginated'), and output format ('HAL+JSON with reaction type, timestamp, and recipient details'). Could mention error conditions or rate limits for a 5.

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?

Five sentences with zero waste: purpose, use case, filters, sibling alternative, and output format. Every sentence earns its place with optimal information density.

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?

Compensates well for missing output schema by describing return format and pagination. Covers read-only nature without annotations. Adequate for 12-parameter tool, though could note that all parameters are optional (0 required).

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% description coverage, establishing baseline of 3. Description groups parameters into categories ('reaction type, recipient, event, sending, or date range') which aids comprehension but doesn't add critical semantic detail beyond schema.

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?

Excellent specificity with 'List recipient reactions (opens and clicks) for transactional emails' - clear verb, resource, and scope. Distinguishes from siblings by specifying 'transactional' vs relay.

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?

Explicit usage context ('track engagement — who opened or clicked links in event-triggered emails') and clear sibling differentiation ('For mail relay reactions, use list_relay_reactions instead').

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