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

Annotations already declare readOnlyHint=true, destructiveHint=false and openWorldHint=true, so the safety profile is covered. The description adds the underlying GET endpoint and the shape of the result, but says nothing about pagination behavior (limit/offset/next_offset), rate limits, or empty-result handling.

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?

Two tight sentences that lead with what the tool returns, followed by the required-parameter note. The trailing raw endpoint string ('GET /api/v1/statistics/event/meta') adds little for an agent and is the one slightly wasteful element.

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?

With no output schema, the description correctly compensates by naming the returned fields (count, visitors, conversion rate). For an 11-parameter read tool it is nearly complete, missing only notes on pagination and sorting behavior that the schema partially implies.

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 every parameter (including tz, sort, direction, limit, offset, search) is already documented in the schema. The description's only parameter remark, that event and event_meta_key are required, is redundant with the schema's required list, so baseline 3 applies.

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 names a specific resource ('the values of one metadata key of one event') and enumerates the returned metrics (count, visitors, conversion rate), which tells an agent exactly what it gets. It is clear on its own but does not explicitly distinguish itself from close siblings like pirsch_get_tag_breakdown or pirsch_list_events.

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 only guidance is 'Both event and event_meta_key are required', which restates a schema constraint rather than telling the agent when to pick this tool over pirsch_list_events, pirsch_list_event_pages or the tag breakdown. No when-not conditions or alternatives are offered.

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