Zapmail MCP Server

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

With no annotations provided, the description carries full burden for behavioral disclosure. It states the tool enables catch-all forwarding but doesn't cover critical aspects: whether this is a mutating operation (likely yes, given 'Add'), permission requirements, rate limits, side effects (e.g., impact on existing email routing), or what happens on success/failure. The description is functional but lacks operational context needed for safe invocation.

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 efficiently structured in two sentences: the first explains the functionality, and the second provides a generic invocation instruction. It's front-loaded with the core purpose and avoids unnecessary elaboration. However, the second sentence ('Invoke this endpoint') is somewhat redundant given the tool context, slightly reducing conciseness.

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 tool that likely performs a mutating operation (enabling catch-all emails) with 7 parameters, no annotations, and no output schema, the description is insufficient. It lacks details on behavioral traits (e.g., idempotency, error handling), expected inputs/outputs, and dependencies. The high parameter count and absence of structured safety information make this description incomplete for reliable agent use.

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 description coverage is 100%, so the schema fully documents all 7 parameters. The description adds no parameter-specific information beyond implying domain and recipient parameters (via 'your domains' and 'specified recipient'), but these aren't mapped to actual schema properties like 'pathParams' or 'body'. Baseline 3 is appropriate as the schema does the heavy lifting, though the description doesn't compensate with additional semantic context.

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: 'Add catch-all email functionality for your domains' with the specific action of forwarding undefined addresses to a specified recipient. It uses a specific verb ('Add') and resource ('catch-all email functionality'), but doesn't explicitly differentiate from sibling tools like 'enable_email_forwarding_13521023e0' or 'remove_catch_all_emails_13521079e0' beyond the enable/remove 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?

The description provides no guidance on when to use this tool versus alternatives. It doesn't mention prerequisites (e.g., needing domains configured), exclusions, or compare it to related tools like 'enable_email_forwarding_13521023e0' or 'add_domain_forwarding_13520843e0'. The phrase 'Invoke this endpoint' is generic instruction, not contextual guidance.

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