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

Annotations already declare this a safe, idempotent, closed read, and the description adds substantial behavior on top: caveats must be read before reporting figures, an unreadable range is refused rather than silently shifted (naming the site's today), filters cap at 6 and one per dimension, and filters matching nothing yield other_values_containing and suggestions. This is exactly the kind of error/edge-case disclosure annotations cannot carry.

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?

It is front-loaded—the first clause states the resource and the comparison period—and dense rather than padded, with each clause carrying a distinct rule or returned field. The prose is extremely compressed and run-on, which strains readability, but for a 7-parameter tool with no output schema most sentences earn their place.

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 carries the full return-value burden and does so: it enumerates echoed inputs, dashboard link, totals, previous, change (percentages vs points, null where none), per_day, basis, ended_visits, series and top, and details special filter semantics (goal filters return conversions/events/rate) plus empty-result fallbacks. Nothing an agent needs to call or interpret this correctly is missing.

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 coverage is 100%, so the baseline is 3, but the description adds a genuinely non-schema fact: the three temporal specifications are mutually exclusive ('the range one way: range...; days...; or from and to'), plus the default (7 whole days to yesterday) and filter rules (max 6, one per dimension, each narrows every figure). These add meaning beyond the raw property descriptions.

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 and scope: a site's figures over a range plus the preceding period, enumerating exactly which metrics come back (pageviews, visits, visitors, bounce rate, visit duration, changes, by day/week/month, and top channels/sources/pages/countries). An agent knows precisely what this tool yields, but it never explicitly differentiates itself from the potentially overlapping get_overview sibling, so it stops 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?

Usage is implied rather than stated: you call this to get a site's summarized figures. The description gives rich rules for how to call it (range one way, or days with ending, or from/to; default is the 7 whole days to yesterday) and pointers to siblings for enumerating values (get_site_breakdown for channels/properties, list_sites, list_goals), but it never says when to prefer this over get_overview, get_site_breakdown, or get_site_engagement.

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