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 but offers minimal behavioral insight. It hints at 'two payment modes' but doesn't explain them, and 'Invoke this endpoint' is vague. Critical details like required permissions, rate limits, side effects (e.g., whether it's a read-only or mutative operation), or expected outcomes are missing. The description adds little value beyond the tool name.

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 brief but poorly structured and incomplete. The first sentence is clear but generic, while the second sentence is fragmented and adds no value ('Invoke this endpoint' is redundant). It fails to front-load essential information, and the incomplete thought wastes space rather than being concise.

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 complexity implied by 7 parameters and no annotations or output schema, the description is insufficient. It doesn't explain what a 'placement test' is, how it works, what it returns, or its behavioral traits. For a tool with potential mutative or financial implications (suggested by 'purchase' in the name), this lack of context is a significant gap.

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 what the schema provides, such as how 'method' or 'path' relate to placement tests. Baseline 3 is appropriate as the schema handles parameter documentation adequately.

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 'Run placement tests on selected mailboxes' states a general action but lacks specificity—it doesn't clarify what a 'placement test' entails or how it differs from siblings like 'get_eligible_mailboxes_for_placement_tests_25779778e0'. The second sentence 'Supports two payment modes: Invoke this endpoint' is incomplete and confusing, adding no clarity. This is borderline tautological, as it mostly restates the title without meaningful elaboration.

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?

No guidance is provided on when to use this tool versus alternatives. The description does not mention prerequisites, context, or exclusions, and it fails to differentiate from sibling tools like 'get_placement_test_orders_25779469e0' or 'purchase_plan_25780426e0'. The incomplete second sentence offers no practical usage advice.

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