Zapmail MCP Server

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

No annotations are provided, so the description carries full burden. It discloses the calculation method ('subtracting used slots from your total slots'), which is useful behavioral context. However, it fails to mention critical traits like authentication requirements, rate limits, error conditions, or whether this is a read-only operation (implied by 'Check' but not explicit). For a tool with no annotations, this leaves significant gaps in behavioral understanding.

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 three sentences: purpose, calculation method, and invocation instruction. Each sentence adds value without redundancy. However, the final sentence 'Invoke this endpoint' is slightly redundant with the tool's nature, slightly reducing conciseness. Overall, it's well-front-loaded and appropriately sized.

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 moderate complexity (calculating slot availability across subscriptions), no annotations, and no output schema, the description provides a clear purpose and calculation logic but lacks details on authentication, error handling, or return format. It's minimally adequate for understanding what the tool does but incomplete for reliable use without additional context or trial.

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 (e.g., 'method', 'path', 'workspaceKey'). The description adds no parameter-specific information beyond the general action, such as which parameters might be relevant for this endpoint. Given the high schema coverage, the baseline score of 3 is appropriate, as the description doesn't compensate but doesn't detract either.

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 specific action ('Check how many available DNS Shield slots you have') and resource ('across all your LTD subscriptions'), with explicit calculation details ('total available capacity by subtracting used slots from your total slots'). It distinguishes from sibling tools by focusing exclusively on DNS Shield slot availability, unlike tools like 'get_allocated_domains_for_subscription_25781672e0' or 'get_eligible_domains_25781361e0' that handle different resources.

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 implies usage context through 'across all your LTD subscriptions' and 'active LTD plans', suggesting it's for users with lifetime deals. However, it lacks explicit guidance on when to use this tool versus alternatives (e.g., 'get_subscriptions_25781447e0' for subscription details) or any exclusions (e.g., not for non-LTD plans). The context is clear but incomplete for sibling differentiation.

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