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

Annotations already mark this as a non-read-only, open-world, non-destructive mutation. The description adds useful operation-specific context: creation happens in the asset library, the response may include an identifier or a validation/platform error, and attachment is not performed. It omits auth/idempotency details but adds enough beyond annotations.

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?

Three tight sentences, front-loaded with the action and scope; no redundant repetition. The separate-attachment note earns its place by preventing scope confusion.

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?

The description covers the high-level operation and return/error shape, which is important because there is no output schema. However, for a 13-parameter create tool with almost no schema descriptions, it leaves the agent dependent on field names and types for correct invocation, so it is not fully complete.

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 8% (only `url` is documented), and the description contributes nothing beyond 'using the supplied fields'. With 13 parameters and complex fields like `email_lead_form_user_input_types`, it does not compensate for the low schema coverage.

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 (Create) and resource (lead form extension) and locates it in the Google Ads asset library, which distinguishes it from the many sibling create_google_*_extension tools. An agent can identify the correct extension type without opening the 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 clarifies the important boundary with campaign attachment ('Attaching the extension to a campaign is a separate operation'), which is the most likely misuse. It does not explicitly name add_extensions_to_native_campaign or explain when to choose a lead form extension over other extension types, so it stops short of full alternative routing.

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