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

Beyond the annotations (destructiveHint=true, idempotentHint=false, openWorldHint=true), the description discloses that every call creates a user-approved proposal before anything changes, that creations default to PAUSED, and that calls are constrained to one account with no fan-out. These are consequential behaviors the annotations alone do not convey.

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?

Front-loaded with the routing rule and invocation signature before the catalog, and the length is justified by the need to enumerate 38 dispatch targets. Minor redundancy between 'reading, listing or checking anything is not here' and 'calling this router to look something up is always wrong', but the emphasis is arguably warranted for a misrouting-prone router.

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 mutation router with no output schema, the description covers what the agent needs: how to invoke it, which sub-tools exist, the approval/paused-creation workflow, and the one-account constraint. Nothing required for correct calling 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 100% and the schema already explains action/arguments/tool_name, so the baseline is 3. The description adds real value for tool_name by enumerating the 38 valid values grouped by category, which the schema only bounds by minLength/maxLength 64.

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 ('the 38 Google Ads tools that create, update, pause or remove something') and explicitly names the read sibling google_ads as the thing it is not. An agent can distinguish it from every sibling 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?

Gives explicit when-not guidance ('reading, listing or checking anything is not here — that is google_ads, and calling this router to look something up is always wrong') and points to the free schema lookup path via google_ads(action="get_tool_schema"). The alternative and its selection condition are both stated.

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