Mixpanel MCP Server

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

With no annotations provided, the description carries the full burden of behavioral disclosure. It mentions the tool is 'useful for tracking averages,' which implies a read-only, analytical function, but doesn't specify if it requires authentication, has rate limits, returns data in a specific format (e.g., time-series), or handles errors. This leaves gaps in understanding its operational 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 front-loaded with the core purpose in the first sentence and includes a concise second sentence for context. Both sentences earn their place by clarifying functionality and use cases without redundancy, making it efficient and well-structured.

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 (6 parameters, no annotations, no output schema), the description is adequate but incomplete. It covers the basic purpose and hints at usage, but lacks details on output format, error handling, or behavioral constraints, which are crucial for an agent to invoke it correctly without structured support.

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, clearly documenting all 6 parameters. The description adds minimal value beyond the schema by implying the 'on' parameter is numeric and mentioning an example ('order value'), but doesn't provide additional syntax or usage details. This meets the baseline score since 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: 'Get the average of a numeric event property over time.' It specifies the verb ('Get the average') and resource ('numeric event property over time'), making it easy to understand. However, it doesn't explicitly differentiate from sibling tools like 'segmentation_sum' or 'query_insights' that might also involve event analysis.

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 implied usage guidance with 'Useful for tracking averages like order value,' suggesting contexts for application. However, it lacks explicit instructions on when to use this tool versus alternatives such as 'segmentation_sum' for sums or 'query_insights' for other metrics, and doesn't mention prerequisites or exclusions.

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