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

Annotations only say it's a non-read-only, open-world, non-destructive write. The description adds real behavioral detail beyond that: pre-validation of character limits, the specific error code text_too_long, the partial-failure mode link_failed that still returns an asset_id, and the correct recovery action. It also notes workspace may be omitted when only one exists.

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?

Dense but front-loaded: creation and linking rule first, then constraints, then response and failure recovery. Every sentence carries information, though restating the response fields (status/asset_id/linked_to) is slightly redundant given an output schema exists.

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 6-parameter mutation with zero schema documentation coverage, the description supplies limits, level selection, partial-failure semantics, and recovery routing. An agent can invoke this correctly and handle the main failure mode without further exploration.

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 burden and largely meets it: max lengths for link_text and description1/2, the meaning of campaign_id (omitted = account level), and the semantics/default of workspace. The one gap is final_url, whose expected format (full URL with protocol, landing page requirements) is not explained anywhere.

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 and resource (create a sitelink asset) plus the scope decision (link to campaign via campaign_id, otherwise account level). This cleanly distinguishes it from ads_update_sitelink (modify) and ads_link_asset (link-only, which it explicitly names).

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?

Gives the branching rule for campaign vs account level ('Ohne campaign_id Konto-Ebene') and an explicit alternative path: if only linking fails, call ads_link_asset(asset_id, 'SITELINK') rather than recreating. That is exactly the when/when-not/alternative guidance an agent needs.

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