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

Annotations already declare destructiveHint=true, idempotentHint=true and readOnlyHint=false, so the safety profile is covered. The description adds genuinely useful scope detail beyond that: already-sent messages are unaffected and remaining sends halt, clarifying what 'destructive' means here. It stops short of stating effects on scheduled-but-unsent future batches or what is returned.

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 core action front-loaded and no filler; the second sentence earns its place by defining the blast radius.

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 simple state-change tool with full annotation coverage, complete parameter documentation, and no output schema, the description supplies the one thing annotations cannot: the effect boundary on in-flight sends. Minor gap is that it does not say what the call returns or how it behaves if the campaign is already paused.

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% with two documented parameters, so the baseline is 3. The description adds no interpretation of campaignId or the apiKey override beyond what the schema already states.

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 ('Pause') and resource ('sending campaign'), so the action is unambiguous. It does not explicitly contrast itself with the close sibling pause_automation, leaving the agent to rely on the resource noun alone.

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 gives no when-to-use guidance and never names the obvious alternatives (resume_campaign, pause_automation, delete_campaign) or the conditions that would select one over another. Usage must be inferred entirely from the tool name.

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