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. While it indicates this is a write operation ('add billing information'), it doesn't mention required permissions, whether this is a one-time setup or can be modified, what happens if billing details already exist, or any rate limits. The description is minimal and lacks important behavioral context for a billing-related mutation.

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 the second sentence 'Invoke this endpoint' is redundant and adds no value. The first sentence contains the core information but could be more efficiently structured. While not verbose, it includes unnecessary filler.

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 billing mutation tool with 7 parameters, no annotations, and no output schema, the description is insufficient. It doesn't explain what happens after adding billing details, what format the billing information should take, whether this triggers any billing processes, or what errors might occur. The description leaves too many important contextual questions unanswered.

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. The description mentions 'billing details include the user's name, company, address, and contact information' which hints at what might go in the body parameter, but doesn't provide specific structure or format details beyond what the generic schema descriptions already indicate. 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 action ('add billing information') and resource ('for a workspace'), with specific details about what information is included (name, company, address, contact). However, it doesn't differentiate from the sibling tool '_update_billing_details_13517578e0' which appears to handle updates rather than initial addition.

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. There's no mention of prerequisites, when billing details should be added, or how this differs from the update_billing_details sibling tool. The phrase 'Invoke this endpoint' is generic and adds no contextual guidance.

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