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 endpoint (GET /api/v1/statistics/events) and the metric set, which is useful, but says nothing about pagination behavior, rate limits, or how the 33 filters combine. Adequate but not rich.

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 short sentences with no filler; the alternative-tool routing is placed after the resource statement in a logical order. The first sentence is a bare noun phrase lacking a verb, which is slightly abrupt, but nothing is wasted.

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 33 parameters and no output schema, the description usefully enumerates the returned metrics so an agent can judge relevance, and the fully documented schema covers inputs. Only pagination/result-envelope behavior is left unexplained, which is a minor gap.

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%, including the offset hint about next_offset and the tag/event_meta pair semantics, so the schema carries the full parameter burden. The description contributes no parameter-level meaning beyond that. 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 the concrete resource (custom events) and enumerates the metrics returned (count, visitors, views, conversion rate, average duration, metadata keys), so an agent knows exactly what comes back. It also separates itself from pirsch_get_event_breakdown. It never states the verb 'list' or a scope/filtering statement in the description text itself, only the title does, so it falls just short of a 5.

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?

It gives an explicit routing rule: use pirsch_get_event_breakdown when you want the values of one metadata key, otherwise use this tool. That is a clear alternative for the most likely confusion case. It offers no negative conditions or prerequisites (e.g. that domain_id comes from pirsch_list_domains), but the single routing sentence is solid.

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