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

Annotations already declare destructive, idempotent, and openWorld behavior, so the bar is lower; the description still adds real value by disclosing partial-failure semantics ('an id from another workspace reports not_found without failing the rest'), which is not derivable from the annotations. It stops short of saying whether pausing is reversible or what happens to active ads mid-flight.

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, zero filler, with the action and limit front-loaded and the error-handling nuance immediately after. Nothing could be removed without losing information.

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 two-parameter mutation with no output schema, the description covers the key things an agent needs: the size limit, the status semantics, and per-id error behavior. The only gap is the exact shape of the per-id result payload, which 'Per-id results' only gestures at.

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?

With 0% schema description coverage, the description carries the burden well: 'Start or pause' maps the status enum to active/paused semantics, and 'up to 100' restates the maxItems bound with intent. It still doesn't explain the ids array element type or what happens with duplicate ids.

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 pair ('Start or pause'), the resource ('campaigns'), and the bulk scope ('up to 100 at once'), which cleanly distinguishes it from the singular sibling set_campaign_status without needing to name it explicitly.

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 phrase 'up to 100 campaigns at once' implies this is the tool to pick when acting on multiple campaigns, but it never states an explicit when-not condition or points to set_campaign_status for single-campaign updates. Usage is inferable rather than spelled out.

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