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 of behavioral disclosure. While 'update' implies a mutation operation, the description fails to mention critical behavioral aspects: required permissions, whether changes are immediate or require verification, potential side effects (e.g., billing cycle impacts), or error conditions. It also doesn't specify if this affects active subscriptions or payment methods.

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 (two sentences) but inefficiently structured. The first sentence is useful; the second ('Invoke this endpoint') is redundant procedural instruction that doesn't add value. While not verbose, it could be more front-loaded with critical context about the tool's role in the billing workflow.

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 mutation tool with 7 parameters, no annotations, and no output schema, the description is incomplete. It lacks information about required permissions, response format, error handling, and how it integrates with sibling tools (especially 'add_billing_details'). The high parameter count and mutation nature demand more contextual guidance than provided.

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 already documents all 7 parameters thoroughly. The description mentions updatable fields (name, company, address, contact details) which loosely map to potential 'body' content, but doesn't add meaningful semantics beyond what the schema provides about parameter usage or relationships. The baseline of 3 is appropriate when the schema does the heavy lifting.

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 tool's purpose: 'update billing information for a workspace' with specific fields (name, company, address, contact details). It distinguishes itself from siblings like 'add_billing_details' by focusing on updates rather than creation. However, it doesn't explicitly differentiate from other update tools like 'update_workspace' or 'update_third_party_account_details'.

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 doesn't mention prerequisites (e.g., existing billing details to update), nor does it differentiate from sibling tools like 'add_billing_details' (for initial setup) or 'update_workspace' (which might handle broader workspace updates). The phrase 'Invoke this endpoint' is procedural rather than contextual guidance.

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