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

Annotations already declare destructiveHint=true, readOnlyHint=false and openWorldHint=true, so the mutation and external-side-effect profile is covered. The description adds genuinely new behavior — the link is only an invitation that must be accepted inside Merchant Center — which an agent could not infer from the annotations. It does not say whether unlinking revokes immediately or what the response contains.

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 short sentences with zero filler: the action, the two-step acceptance caveat, the sibling pointer, and the business rationale all appear in order of importance. Nothing is repeated from the schema or annotations.

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 destructive, externally visible mutation with no output schema and 25% schema coverage, the description should specify which parameters each action requires and what the caller must do next. It covers the acceptance step but leaves the argument-to-action contract undefined.

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 only 25%, with just 'account' documented, and the description adds no parameter meaning at all. The critical mapping of which identifiers each action needs — merchant_center_id for link, product_link_id for unlink — is left entirely implicit, forcing the agent to guess from field names.

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 verb+resource pair for both modes: send a link invitation to a Merchant Center account, or remove a link. It distinguishes itself from the sibling it would otherwise be confused with by pointing at google_ads_merchant_links for viewing existing links, so an agent can separate read from write without opening a schema.

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?

It gives a clear trigger for use ('Needed for Shopping and retail Performance Max') and routes the read-only case to google_ads_merchant_links. It does not state prerequisites (admin access on both sides) or when unlinking is appropriate, so it stops short of full when/when-not guidance.

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