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

Annotations already mark this as a non-destructive write, and the description adds meaningful context beyond them: the link has no unlink tool, so it persists; linking shares audience and remarketing data when personalization is enabled; and duplicates are preventable by checking first. Those are exactly the side effects an agent needs before calling a mutation.

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?

Four tight sentences: purpose and rationale first, parameter formats next, then prerequisite and irreversibility. Every sentence adds information an agent can act on.

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?

All three parameters are explained despite zero schema descriptions, the prerequisite is named, and the output schema handles return values. Nothing needed to call it 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 0%, so the description carries the full burden. It gives the property format ('properties/<id>'), says customer_id is the Ads account number with hyphens stripped, and explains that ads_personalization_enabled defaults off and what it actually enables.

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 ('Link') and both resources (GA4 property and Google Ads account) and explains the effect on key events and paid/organic traffic. It also distinguishes itself from the sibling ga4_list_google_ads_links and notes there is no unlink counterpart.

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 instructs to read ga4_list_google_ads_links first so an agent avoids creating a duplicate link, and says ads_personalization_enabled should stay off unless the user asks. That covers both when to use it and how to gate the risky option.

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