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 that results are bucketed per interval and points to the scale parameter, which is useful behavioral context. However, it says nothing about defaults, filtering semantics across the 26 optional filters, or result volume for long ranges.

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?

Three short sentences: returned payload first, usage second, endpoint third. Front-loaded and waste-free, though the raw GET path adds little for an MCP agent and the "(see scale)" parenthetical is slightly awkward.

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 29 parameters, nested tag/event_meta objects and no output schema, the description should ideally sketch the return shape (e.g. one row per interval). It names the metrics but not how they are keyed or ordered, leaving a meaningful gap for a heavy time-series endpoint.

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% across all 29 parameters, so the schema carries full parameter documentation. The description only gestures at scale ("see scale"), adding no syntax or semantics beyond the schema. 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?

It names the specific metrics returned (visitors, views, sessions, bounces, bounce rate) and the granularity (per day/week/month/year), which is a concrete verb+resource statement. It is distinguishable from aggregate siblings like pirsch_get_totals, though it never names an alternative explicitly.

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?

"Use it for traffic charts and trends" gives an implied usage context, but there is no when-not guidance and no routing among the many close siblings (get_totals, get_growth, get_time_distribution, get_overview). The agent must infer differentiation from the metric list alone.

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