Render a campaign's HTML preview as subscribers would see it, read-only with nothing sent. Use it to verify content and layout before sending or scheduling the campaign.
Render a preview of the campaign as the HTML subscribers would see. Read-only: nothing is sent. Use it to check a campaign before send_campaign or schedule_campaign.
| Name | Required | Description | Default |
|---|---|---|---|
| campaign_id | Yes | Campaign ID |
Changes observed during successful MCP inspections.
Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
Annotations already declare readOnlyHint=true; the description reinforces this with 'nothing is sent,' which is meaningful for an agent worried about triggering a real send. It also implicitly characterizes the return value as rendered HTML, though it omits any note on rendering failures, caching, or size limits.
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 no waste; the purpose comes first and the safety/workflow note follows. 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 one-parameter read tool with no output schema, the description covers what it produces (subscriber-view HTML) and that it is side-effect free. Minor gap: no mention of what happens for unsent/draft campaigns or whether personalization is resolved.
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 a single required campaign_id (number, exclusiveMinimum 0), so the schema carries the parameter burden. The description adds no further constraint such as whether the ID must refer to an existing draft — baseline 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?
States a specific verb and resource ('Render a preview of the campaign') plus the exact output form ('as the HTML subscribers would see'). This clearly distinguishes it from get_campaign (metadata retrieval) and get_templates.
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?
Explicitly names the moment to use it — checking a campaign before send_campaign or schedule_campaign — which routes the agent to the right sibling tools at the right workflow stage. No ambiguity about when this tool applies.
Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.