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

Annotations already convey readOnlyHint=false and destructiveHint=false, so the bar is lower. The description adds genuine behavioral value: the clock keeps running after pausing (cost continues), and it discloses the auth requirement (Bearer JWT). It does not mention the reversibility or response shape, but with annotations covering the safety profile, these additions are meaningful.

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 zero filler. The core action is front-loaded, the key side effect ('clock keeps running') is attached immediately, and the auth requirement is stated compactly. Every clause earns its place.

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 single-parameter, mutation-type tool with annotations present, the description covers purpose, side effect, and auth. It omits return-value behavior and error conditions, but given the simplicity of the tool (one integer param, no output schema) and annotation coverage, the remaining gaps are minor.

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 0%, so the description must compensate, but it never mentions the sole required parameter 'id' or what it refers to. While an agent could infer that id is the campaign ID from the tool name, the description itself adds no parameter-level meaning, leaving the mapping implicit.

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 ('Stop a live campaign') with a clarifying behavioral qualifier ('from being recalled or served'). The parenthetical about the clock distinguishes this from destructive or terminal actions, and the tool name distinguishes it from siblings like ads_campaign_resume and ads_campaign_update.

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 description implies usage on live campaigns and notes billing continues, which gives some context for deciding to pause. However, it provides no explicit when-to-use vs alternatives, does not name ads_campaign_resume as the inverse, and does not mention any exclusions (e.g., already-paused campaigns or ordering constraints). Usage is inferred rather than stated.

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