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

Annotations already declare readOnlyHint=true, destructiveHint=false, and openWorldHint=false, so the description's extra value is 'unsaved' (explicitly confirms the preview creates nothing) and 'source fingerprint' (provenance metadata returned). That is useful added context, but it omits what happens on a non-owned or missing ad_id and whether any rate/permission constraints apply.

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?

A single front-loaded sentence with no padding; verb, scope, and return shape all appear in the first clause. Nothing extraneous to cut.

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?

An output schema exists, so return values needn't be spelled out, and the read-only safety profile is covered by annotations. However, for a 5-parameter tool at 20% schema coverage, the description leaves real gaps around the undocumented name/connection_context parameters and the prerequisite relationship between ad_group_id and ad_id.

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 20% (only customer_id is documented), and the description adds no parameter-level meaning: it does not explain that ad_group_id must be the parent of ad_id, what 'name' is used for on a read tool, or what connection_context does. With low coverage, the description needed to compensate and does not.

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: reads one owned responsive search ad and returns an unsaved normalized template preview plus a fingerprint. That is far more informative than the tool name alone, though it never names the sibling it complements (google_ads_template_save / google_ads_templates_list), leaving the reverse-engineer-to-template workflow implicit.

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 word 'unsaved' implies a preview-then-save workflow and 'owned' implies the ad must already exist in a connected account, but there is no explicit when-to-use, when-not-to-use, or alternative named. An agent must infer that this is the read-side counterpart to the template save/update tools.

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