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

Annotations already declare readOnly/idempotent/non-destructive/openWorld, so the safety profile is covered. The description adds the meaningful default of 'last 30 days' for the date range, but says nothing about pagination, result size, or rate limits for what is effectively an analytics query.

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?

Two tight sentences: a definition followed by a concrete example. It is front-loaded and every clause carries information, with only minor room to tighten.

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 an 8-parameter, low-coverage, no-output-schema analytics tool, the description gives a helpful example and the date default but doesn't cover the full parameter surface or what the report returns, leaving meaningful gaps for an agent to resolve.

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 low (38%), so the description should compensate. It does partially: it introduces the dimensions/metrics model and gives a concrete example, and it clarifies the date-range default. However, it is silent on limit, orderBy, filters, and the required property parameter, leaving those halves unexplained in both places.

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 verb and resource ('custom report with chosen dimensions and metrics for a date range') and the word 'custom' implicitly contrasts with the many preset sibling reports (adsense_earnings, adsense_by_country, adsense_top_pages). It's clear what the tool does, though it never explicitly routes the agent away from those presets.

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?

There is no explicit when-to-use guidance. The agent is left to infer that this tool is for ad-hoc dimension/metric combinations versus the ten-plus sibling report tools, and no conditions or prerequisites (e.g. needing a property id) are stated.

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