Inxmail MCP

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

With no annotations provided, the description carries the full burden excellently. It discloses write-operation status, warns about the historical failure context, explains the auto-re-add behavior ('may be re-added automatically if it bounces again'), and documents the return value ('Returns empty response on success').

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: sentence 1 defines purpose, sentence 2 warns about write semantics, sentence 3 discloses side effects, and sentence 4 documents return behavior. Front-loaded with the core action and appropriately sized for the tool complexity.

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 no output schema and no annotations, the description is complete. It covers the action, safety implications, behavioral side effects, and return value, leaving no critical gaps for an agent to invoke this tool correctly.

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 coverage is 100% (the 'email' parameter is described as 'Email address to unblock'), so the baseline is 3. The description implies the parameter purpose through the action description but does not add format constraints, validation rules, or examples 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?

The description opens with a specific verb ('Remove') and resource ('email from the hard-bounce blocklist'), clarifies the outcome ('allowing transactional emails to be sent'), and distinguishes from the sibling 'remove_from_blacklist' by specifying 'hard-bounce blocklist'.

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 cautionary guidance ('use with caution, as the address previously caused a permanent delivery failure') appropriate for a write operation. However, it does not explicitly contrast usage with sibling alternatives like 'check_email_blocked' or clarify when to prefer this over 'remove_from_blacklist'.

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