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

Annotations already cover the safety profile (readOnly, idempotent, non-destructive, openWorld). The description adds valuable context beyond that: the cross-channel aggregation behavior, the same-period alignment, the compare flag adding a previous period, and critically that unlinked/disabled sources are reported explicitly rather than silently omitted. That last point is a real behavioral disclosure an agent cannot get from annotations.

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 tight sentences, front-loaded with the aggregation scope, then the recommendation, then the edge-case behavior. Efficient, though the em-dash phrase is slightly long; 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?

For a read-only aggregation tool with no output schema, the description covers the channels surfaced, the period/compare behavior, and the unlinked-source handling. It stops short of describing the response shape or pagination, but annotations and scope make it sufficient for correct invocation.

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 67%, with client and compare already documented in the schema. The description reinforces the compare behavior ('adding the previous period alongside') but adds no new syntax or semantics for days or client. Baseline 3 is appropriate given the schema carries most of the load.

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 verb+resource ('One client, every channel, one call') and enumerates the exact channels covered (organic search, website analytics, Google Ads, Meta ads, HighLevel) over the same period. Clearly distinguishes itself from the many single-source siblings like ga4_report, ads_report, and meta_insights.

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?

Explicitly says 'This is the right first call for "how is <client> doing"', giving a clear use case and positioning it ahead of narrower siblings. It does not name specific alternatives or say when NOT to use it (e.g., when a single deep-dive channel report is preferable), so it falls short of a 5.

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