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 genuine value by disclosing the return rows (visitors, views, sessions, bounces, relative shares), but says nothing about pagination or rate limits.

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?

Four compact sentences that lead with purpose and modes before filters and results. No filler, though the trailing endpoint path is low-value for an agent that already has the tool name.

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 34-parameter, no-output-schema tool the description does the essential work: it defines the two output modes and describes the returned row fields. Pagination is left to the schema, which is acceptable since offset's description references next_offset.

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 34 parameters, seating the baseline at 3. The description lightly reinforces this by mapping by=referrer/channel and showing filter syntax (country=de, path=~blog), but adds no semantics beyond the schema for the many other filters.

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 states a specific resource and disambiguates its two modes ('referrers (by=referrer) or traffic channels such as Organic Search and Paid Search (by=channel)'). It also names the underlying endpoints. It never names a sibling tool, though, so the boundary with pirsch_list_utm or pirsch_get_overview is left to inference.

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 implies when the tool applies ('Where visitors come from') and explains the by-parameter choice, but gives no explicit when-not guidance and no routing to alternatives like pirsch_list_utm for campaign detail. The filter examples hint at usage without stating conditions.

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