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

Annotations already establish that this is a non-destructive write (readOnlyHint=false, destructiveHint=false, openWorldHint=true), so the description's job is to add link semantics. It does clarify that the operation reuses an existing asset rather than creating one, and that the target can be the account rather than a campaign, but it says nothing about idempotency, what happens if the link already exists, or what permissions are required.

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?

The text is short and front-loaded: the core action and the duplicate-avoidance rationale come first, followed by field_type examples and the workspace note. A few parenthetical asides and a line break inside a sentence slightly interrupt the flow, but 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?

There is an output schema, so return values need not be described, and the safety profile comes from annotations. However, for a 4-parameter mutation with 0% schema coverage, the omission of what asset_id expects and the explicit rule for when campaign_id should be omitted leaves a real gap 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 description coverage is 0%, so the description carries the full burden, and it only partially compensates: it explains field_type with concrete enum-like examples and explains that workspace is optional when there is a single workspace. It never explains asset_id, and it only implies (rather than states) that campaign_id is optional and that omitting it links at the account level.

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 ('Bestehendes Asset ... mit einer Kampagne oder dem Konto verknüpfen') and adds the key differentiator, 'statt ein Duplikat anzulegen', which distinguishes it from the create-style siblings such as ads_create_sitelink. It does not name the closest siblings (ads_unlink_asset, ads_create_sitelink) explicitly, so the differentiation is implied rather than spelled out.

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?

The description implies when to use it (reuse a shared asset instead of duplicating it) and gives examples of valid field_type values, but never states an explicit when-not-to-use condition or names the alternative tools. An agent still has to infer that it should use ads_create_sitelink when no asset exists.

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