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

Annotations already flag destructiveHint=true and openWorldHint=true, so the bar is lower, yet the description adds real value by splitting risk per action: three actions run directly, detach needs confirmation. It also states the spend consequences of each direction. It omits mention of `dry_run` and of what a create returns, which keeps it from a 5.

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 with the action inventory front-loaded and the risk/confirmation note second. Every clause carries information; nothing is restated 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 an 8-parameter mutation tool with no output schema, the definition covers the action set, the spend implications, and the confirmation requirement well, and annotations carry the safety profile. It would be stronger if it explained the two-phase `confirm`/`dry_run` workflow or named the sibling tools it supersedes for shared lists.

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 63%, so the baseline is 3. The description adds meaning for `keywords` (used with create), `campaign_ids` (attach), and implicitly `confirm` (needed for detach), but leaves `list_id`, `account`, `dry_run`, and match types to the schema, so it does not fully compensate for the coverage gap.

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+resource ('Manage shared negative keyword lists') and enumerates the four supported actions that match the `action` enum exactly. An agent can tell this is a shared-list lifecycle tool. It stops short of naming siblings, so it does not explicitly differentiate itself from `google_ads_add_negative_keywords` (campaign-level negatives) or `google_ads_negative_lists` (likely the read side).

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 second sentence gives clear selection context: create/add/attach reduce spend and execute immediately, while detach widens reach and requires confirmation. That tells the agent when extra care is needed. It does not route the agent between this tool and the per-campaign negative keyword siblings, which is the main remaining gap.

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