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 retrieves information (implying read-only) and describes the return format, but lacks details on permissions, rate limits, error conditions, or whether it's idempotent. The phrase 'Invoke this endpoint' is redundant and adds no behavioral insight.

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 two sentences, but the second sentence ('Invoke this endpoint.') is unnecessary and adds no value. The first sentence is information-dense but could be more front-loaded; it efficiently covers purpose and output details, though the structure is adequate but not exemplary.

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 read operation with no annotations and no output schema, the description adequately explains what the tool does and what it returns. However, it lacks context on authentication, error handling, or system behavior, which would be helpful given the tool's apparent role in a billing/subscription system. It's minimally complete but leaves gaps in operational guidance.

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 the tool might not require inputs (since it describes retrieving 'across all active subscriptions' without mentioning parameters). This meets the baseline for high schema coverage.

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 verb ('Retrieve information') and resource ('available placement test credits (slots) across all active subscriptions'), with specific output details ('total available credits, used credits, and breakdown by subscription'). It doesn't explicitly differentiate from sibling tools like 'get_available_slots_25781438e0' or 'get_placement_test_orders_25779469e0', but the focus on 'placement test credits' provides reasonable 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 mentions no prerequisites, exclusions, or comparisons to sibling tools such as 'get_available_slots_25781438e0' or 'get_placement_test_orders_25779469e0', leaving the agent to infer usage context solely from the tool name and description.

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