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

Annotations already cover the safety profile (readOnly, idempotent, non-destructive, closed-world), so the description's added value is the 28-day data window, the pixel dependency, and the Pro+ entitlement requirement -- real access/auth context. With no output schema, it also carries the return-shape burden and discharges it well, enumerating median active seconds, scroll depth, exit section, and per-section funnel. It does not mention rate limits, empty-state behavior, or what happens when the pixel is off.

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?

Front-loaded with the resource and time window, then the no-path case, then the with-path case, then the entitlement caveat -- a logical build with no filler sentences. Each clause carries distinct information an agent needs before invoking.

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 read-only reporting tool with no output schema, the description covers the data window, entitlement gate, and both result shapes, which is nearly everything needed. Two small gaps: the trailing 'Free.' fragment is ambiguous about plan eligibility, and nothing addresses the limit parameter's effect on the top-pages result size.

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 all three parameters are already documented, including the path/omit semantics that the description largely restates. The description contextualizes what the path parameter unlocks (funnel, click and referrer breakdowns), which is marginally useful, but it never mentions the limit parameter or its default/max, so the 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?

States a specific resource and data source: 'Reader engagement from the Blawgy pixel over the last 28 days,' and unambiguously splits the two modes (top-pages summary vs. single-page profile) with their distinct payloads. An agent can tell what this returns without opening the schema, though it never names or contrasts a sibling such as get_traffic or get_overview, which would fully settle the choice.

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?

Gives a clear precondition for use -- 'Pro+ (pixel must be on in Settings)' -- and tells the agent which invocation shape to pick based on whether it has a path. It stops short of stating when NOT to reach for this tool or which alternative to prefer for general traffic metrics, so routing vs. siblings remains implicit.

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