Zapmail MCP Server

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

With no annotations provided, the description carries the full burden of behavioral disclosure. It mentions that the tool 'retrieves' data (implying read-only), but doesn't address authentication requirements, rate limits, pagination, error conditions, or what format the returned data takes. The description is minimal and lacks important behavioral context needed for safe and effective use.

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?

The description is appropriately concise with three sentences that each serve a purpose: stating the tool's function, explaining what pre-warmed domains are, and providing a call-to-action. It's front-loaded with the core functionality and wastes no words, though the final sentence 'Invoke this endpoint' is somewhat redundant.

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?

Given the tool's complexity (7 parameters, no annotations, no output schema), the description is insufficient. It explains what pre-warmed domains are but doesn't address authentication, response format, error handling, or practical usage considerations. For a tool with this many configuration options and no output schema, more guidance is needed about what the tool returns and how to interpret results.

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?

The input schema has 100% description coverage, so the schema already documents all 7 parameters thoroughly. The description adds no parameter-specific information beyond what's in the schema. According to scoring rules, when schema_description_coverage is high (>80%), the baseline is 3 even with no parameter info in the description.

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 clearly states the tool's purpose: 'retrieves available pre-warmed domains with their associated mailboxes' and explains what pre-warmed domains are ('aged domains with warmed-up mailboxes that are ready for immediate use'). It uses specific verbs ('retrieves') and identifies the resource ('pre-warmed domains with mailboxes'), but doesn't explicitly differentiate from sibling tools like 'get_available_domains_25772286e0' or 'retrieve_all_domains_13520015e0'.

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?

The description provides no guidance on when to use this tool versus alternatives. It simply states 'Invoke this endpoint' without indicating context, prerequisites, or comparisons to sibling tools like 'get_available_domains_25772286e0' or 'retrieve_all_domains_13520015e0'. There's no mention of when this tool is appropriate versus other domain retrieval tools.

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