Inxmail MCP

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

With no annotations provided, the description carries full safety disclosure burden and explicitly states 'This is a write operation — it dispatches a real email'. It mentions return values ('Returns the sending result'). Lacks rate limits or error handling specifics, but covers critical mutation warning and side effects.

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 efficiently cover: purpose, input constraints, safety warning, usage guidance, and return value. No redundant phrases or tautologies. Information is front-loaded with the core action, followed by requirements and warnings.

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?

For a single-parameter tool with complex payload requirements, it adequately explains the RFC 5322 structure and encoding needs. Without an output schema, it acknowledges the return value ('sending result'). Could specify what the result object contains, but sufficient for invocation decisions.

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?

While the schema has 100% coverage describing the 'message' parameter, the description adds crucial constraints not in the schema: specific required headers (From, To, Subject, MIME) and the Base64 encoding requirement. This adds meaningful validation context beyond the structured 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?

The description opens with a specific verb ('Send') and resource ('fully composed RFC 5322 email'), and explicitly scopes it to 'Inxmail's infrastructure'. It distinguishes from siblings by specifying 'custom one-off emails that don't fit an event type template', clearly contrasting with the trigger_event/get_event_type template-based workflow.

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?

Explicitly states when to use ('custom one-off emails that don't fit an event type template') and warns about real-world effects ('dispatches a real email'). The contrast with 'event type template' implicitly identifies trigger_event as the alternative for templated sends, providing clear selection criteria.

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