Zapmail MCP Server

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

No annotations are provided, so the description carries the full burden. It states the tool retrieves data (implying read-only) and mentions the types of subscriptions returned, but lacks details on authentication requirements, rate limits, error conditions, pagination, or response format. For a read operation with zero annotation coverage, this is insufficient.

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 front-loaded with the core purpose in the first sentence, followed by additional scope details. The final sentence 'Invoke this endpoint.' is redundant and could be omitted, but overall it's efficiently structured with minimal waste.

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 with 7 parameters, no annotations, and no output schema, the description is incomplete. It doesn't explain the return structure, error handling, or how parameters like 'method' or 'path' override defaults. Given the complexity and lack of structured data, more behavioral and output context is needed.

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', 'query'). The description adds no parameter-specific information beyond implying the tool might use default values for authentication and path. Baseline 3 is appropriate when the schema handles parameter documentation.

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') and resource ('placement test subscriptions for the authenticated user'), with specific scope details ('both active and cancelled subscriptions, including Monthly recurring subscriptions and LTD plans'). It distinguishes from sibling tools like 'get_all_subscriptions_13489431e0' by specifying the subscription type (placement test).

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 like 'get_all_subscriptions_13489431e0' or 'get_subscriptions_25781447e0'. The description mentions it's for the authenticated user but doesn't specify prerequisites, exclusions, or contextual triggers for selection.

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