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

With no annotations provided, the description carries full behavioral burden and meets it well. It discloses account-level row semantics, the read-mostly nature of Google-automated extensions, the absence of performance metrics in v1, the fact that image assets are never updatable, and the exact ad_account_id format. These are meaningful behavioral details beyond what the schema alone provides.

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 description is dense but every sentence earns its place, covering filters, account-level behavior, automated extensions, downstream use, and platform context. The first sentence is somewhat heavy with parentheses, but overall the text is well-structured and free of filler.

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 tool with no annotations and no output schema, the description is close to complete: it explains what is listed, how filtering works, what the account-level rows mean, when mutation is appropriate, and which identifier format to use. It could add more about the exact return row shape or pagination, but the limit schema and asset_id mention cover the main invocation concerns.

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 75%, so the baseline is already solid. The description adds valuable semantics: campaign_id filters campaign links only, ad_account_id must be a bare 10-digit Google Ads customer ID, and field_type maps to the seven named extension types. It does not discuss limit, but the schema's default/min/max are sufficient for that parameter.

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 opens with a clear verb-resource-scope statement: 'List the extensions ... linked to Google Ads campaigns AND at account level.' It names all seven extension types and explicitly references the managing sibling tool, making it obvious that this is the read/list counterpart to adsap_google_manage_extension rather than a mutation tool.

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 states optional filters ('Optionally filter to one campaign_id ... and/or one field_type'), clarifies that account-level rows with campaign_id null apply to all eligible campaigns, and warns against editing AUTOMATICALLY_CREATED extensions. It also routes modification use cases to adsap_google_manage_extension, though it does not use explicit 'use this when' phrasing.

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