Inxmail MCP

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

With no annotations provided, the description discloses the safety profile ('Read-only'), return format ('paginated HAL+JSON with email and block date'), and business impact ('cannot receive any emails'). Lacks only error-state or rate-limit details.

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: (1) core action, (2) sibling distinction + provenance, (3) business effect, (4) alternatives + return format + safety. Front-loaded and dense with signal.

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?

Despite lacking annotations and output schema, the description fully compensates by specifying read-only status, return structure (HAL+JSON), pagination behavior, and sibling relationships. Complete for a filtered list operation.

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% (ISO 8601 dates, page size/number fully described), establishing baseline 3. Description adds pagination context ('Returns paginated') linking size/page params to behavior but does not elaborate on date range semantics 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?

Opens with specific verb+resource ('List email addresses...blacklisted'), explicitly distinguishes from sibling 'blocklist' via the contrast clause, and clarifies the manual vs. automated population distinction.

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 names two alternatives with distinct use cases: 'Use get_blacklist_entry to check a specific email' and 'check_email_blocked for a combined blocklist+blacklist check', clearly delineating when to use this list tool versus single-entry lookups.

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