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

Annotations already carry the full safety profile (readOnlyHint=true, idempotentHint=true, destructiveHint=false, openWorldHint=true), so the description is not expected to re-state them. But it adds nothing behavioral in their place - no mention that this returns a single campaign's aggregate figures, how metrics behave for campaigns with zero spend, or what happens with an invalid resource name.

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?

One short clause with zero filler, which is good for front-loading, but it is terse to the point of under-specification - it reads as a return-value list rather than a complete tool statement. Conciseness here shades into incompleteness rather than efficiency.

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 tool is a simple read with three well-documented parameters and annotations covering safety, and since no output schema exists the metric enumeration usefully hints at the return payload. What is missing is the acquisition path for campaign_resource and any sense of the result shape (single aggregate vs. per-day rows), which the schema does not cover.

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 100%, with each parameter documented in the schema including the enum values and the LAST_30_DAYS default, so the baseline of 3 applies. The description contributes no additional parameter meaning such as how date_range interacts with CTR computation or which project_id is assumed.

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 is a noun fragment that names the resource (a campaign) and enumerates the metrics returned (impressions, clicks, spend, conversions, CTR), which does distinguish it from google_ads_list_campaigns. However, it supplies no verb of its own and leans on the title's 'Get' to convey the action, so the operation itself is only implied.

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?

There is no statement of when to use this versus google_ads_list_campaigns, no note that a campaign_resource must first be obtained from that sibling, and no guidance on choosing a date_range. The only routing hint ('from google_ads_list_campaigns') lives in the schema, not the description.

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