Mixpanel MCP Server

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

No annotations are provided, so the description carries full burden. It states the tool queries and retrieves data, implying a read-only operation, but doesn't disclose behavioral traits like authentication requirements, rate limits, pagination behavior beyond the schema, or potential side effects. This leaves significant gaps for an agent to understand operational constraints.

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 concise with two short sentences that directly state the tool's function. It's front-loaded with the core purpose and avoids unnecessary details, though it could be slightly more structured by explicitly mentioning the API context upfront.

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 complexity of a query tool with 5 parameters, no annotations, and no output schema, the description is incomplete. It lacks information on return values, error handling, or usage context, which is crucial for an agent to invoke the tool correctly without structured output guidance.

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 fully documents all 5 parameters. The description adds no additional meaning beyond the schema, such as examples of filter expressions or guidance on property selection. This meets the baseline of 3, as the schema handles parameter semantics adequately.

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 verb ('Query') and resource ('user profiles') with the specific API ('Engage API'), making the purpose evident. However, it doesn't explicitly differentiate this tool from sibling tools like 'query_events' or 'user_activity', which might also involve user data, leaving some ambiguity in sibling context.

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 mentions filtering and retrieving user profile data but doesn't specify scenarios, prerequisites, or exclusions compared to other tools in the list, such as 'query_events' for event data or 'list_cohorts' for grouped users.

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