Inxmail MCP

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

No annotations provided, so description carries full burden. Discloses return format ('paginated HAL+JSON'), safety ('Read-only'), and filtering capabilities. Deducting one point because it doesn't mention rate limits, auth requirements, or error handling behavior that would be critical for a listing operation with 8 optional parameters.

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?

Six sentences, zero waste. Front-loaded with core purpose, followed by domain context, sibling differentiation, filtering capabilities, return format, and safety property. Every sentence earns its place with no 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?

Complete for complexity level. Distinguishes from sibling list_sendings clearly, compensates for missing annotations by stating 'Read-only' and return format, and covers the 8-parameter filtering surface adequately given schema coverage. No output schema exists, but description discloses HAL+JSON pagination format.

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 (all 8 params documented), establishing baseline of 3. Description mentions 'Filter by recipient, correlation IDs, or date range' which maps to parameters but adds minimal semantic depth beyond the schema (e.g., doesn't explain what correlation IDs represent or pagination behavior beyond schema's max 500 note).

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 clarity: 'List mail relay sendings' provides specific verb and resource, immediately distinguishes from event-triggered emails with parenthetical '(not event-triggered)', and explains the domain concept ('SMTP relay'). Explicitly contrasts with sibling tool list_sendings.

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 alternative: 'Use list_sendings for event-triggered transactional emails instead.' Also explains when to use this tool: 'when your application sends emails through Inxmail as an SMTP gateway.' Clear when/when-not guidance.

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