Mixpanel 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. It states the tool returns a sum over time, which is helpful, but doesn't describe important behavioral aspects: whether results are aggregated, paginated, cached, or have rate limits; what format the output takes; or any authentication requirements. The description adds minimal behavioral context beyond the basic operation.

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 appropriately concise with two sentences that get straight to the point. The first sentence states the core functionality, and the second provides a use case example. There's no wasted verbiage, though it could be slightly more structured with clearer separation of purpose and guidelines.

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 6-parameter analytical tool with no annotations and no output schema, the description is insufficiently complete. It doesn't explain the return format, aggregation behavior, timezone handling, or how the 'unit' parameter affects bucketing. The example 'revenue' helps but doesn't compensate for missing behavioral and output context that an agent needs to use this tool effectively.

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 6 parameters thoroughly. The description adds no specific parameter information beyond what's in the schema - it doesn't explain parameter relationships, provide examples beyond 'revenue', or clarify how 'where' filters interact with the sum calculation. Baseline 3 is appropriate when 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 sum of a numeric event property over time' - a specific verb (get sum) and resource (numeric event property). It distinguishes from some siblings like 'segmentation_average' (average vs sum) but doesn't explicitly differentiate from all analytical tools like 'query_insights' or 'frequency_report'.

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 minimal usage guidance: 'Useful for tracking totals like revenue' gives a generic use case but offers no explicit when-to-use vs when-not-to-use instructions. No alternatives are mentioned, and there's no guidance on when to choose this tool over similar siblings like 'segmentation_average' or 'query_insights'.

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