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

Annotations already declare destructiveHint=false and readOnlyHint=false; the description adds the reason — pausing only halts spend, so it is a safe, always-permitted mutation. That is genuine added context beyond the annotation block. It stops short of describing reversibility or what happens to in-flight ads, and the non-idempotent hint goes unexplained.

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?

Two short sentences with the action front-loaded and the safety reassurance immediately after. Nothing is padded and nothing is missing for its length.

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?

A simple two-parameter mutation with a full schema, an output schema, and clear annotations — the description covers the essentials. Minor gaps remain around reversibility and behavior on an already-paused campaign, but nothing an agent needs in order to call it correctly is absent.

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%: both campaign_id and the optional reason field are documented in-schema, including that reason is for the log. The description adds nothing beyond that, so the baseline of 3 applies.

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 names a specific verb and resource: "Pause (turn off) a campaign now," with the parenthetical removing any ambiguity about what "pause" means in this domain. It is clearly distinct from siblings like create_campaign, set_ad_budget, and go_live_ad_campaign, though it never explicitly names the resume counterpart.

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?

"Always allowed: it only stops spend" tells the agent there are no preconditions or permission gates, which is useful positive guidance. However, it gives no exclusions, no mention of go_live_ad_campaign as the way back, and no guidance on when a campaign should be paused versus having its budget adjusted.

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