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 discloses that this tool sets default headers for future calls, which implies a stateful or configuration behavior. However, it lacks details on persistence (e.g., how long the context lasts), error handling, or side effects, which are important for a tool that modifies API call behavior.

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 a single, efficient sentence that directly states the tool's purpose without unnecessary words. It is front-loaded with the key action and resource, making it easy to understand quickly. Every part of the sentence contributes to clarifying the tool's function.

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 complexity (configuring context for API calls) and the absence of annotations and output schema, the description is somewhat complete but lacks depth. It covers the basic purpose but does not address behavioral aspects like how the context is applied, potential errors, or interactions with other tools, leaving gaps for an agent to infer usage correctly.

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?

The input schema has 100% description coverage, with clear parameter descriptions (e.g., 'Workspace ID (UUID)' and 'Mail service provider' with enum values). The description does not add any additional meaning beyond the schema, such as explaining the impact of these headers or default values. Since schema coverage is high, the baseline score of 3 is appropriate.

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 ('Set default... headers') and the resource affected ('subsequent API calls'). It distinguishes itself from siblings by focusing on context configuration rather than data operations like adding, retrieving, or updating resources, which are common among the sibling tools.

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 by mentioning 'for subsequent API calls,' suggesting it should be used before making other API calls to set context. However, it does not explicitly state when to use it versus alternatives (e.g., if headers can be set per-call), nor does it provide exclusions or prerequisites, leaving some ambiguity.

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