Inxmail MCP

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

No annotations provided, so description carries full burden. Discloses safety profile ('Read-only') and return value structure ('recipient, event type, timestamps, and delivery status'). Does not mention error handling or rate limits, but covers essential behavioral traits for a lookup operation.

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 structured as: purpose → returns → usage condition → alternative/safety. Zero redundancy; each sentence provides distinct value (what it does, what it returns, when to use it, what to use instead). Efficiently front-loaded with the core action.

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?

Tool has low complexity (1 required parameter, no nested objects) and no output schema. Description compensates by listing specific return fields (recipient, event type, timestamps, delivery status). No gaps remain for this lookup tool's use case.

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?

Input schema has 100% description coverage ('Sending ID'), establishing baseline of 3. Description reinforces with 'by its ID' and contextualizes origin ('from list_sendings or get_event_state'), but does not add syntax details, format specifications, or validation rules beyond the 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?

Description opens with specific verb ('Get') + resource ('transactional email sending') + scoping ('by its ID'). Explicitly distinguishes from sibling 'get_relay_sending' by specifying 'transactional' vs 'mail relay' sendings, preventing tool selection errors.

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 ('when you have a specific sending ID from list_sendings or get_event_state') and clear alternative routing ('For mail relay sendings, use get_relay_sending instead'). This prevents incorrect usage for relay mail vs transactional mail lookups.

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