preview_whatsapp_campaignPreview a campaign's message. Checks that the campaign's template and variable mapping would send, and renders the placeholder values for up to three real recipients (the first materialized recipients once the campaign has started, otherwise contacts from the audience). Writes nothing. Administrators only. Requires feature: whatsapp_campaigns.
| Name | Required | Description | Default |
|---|---|---|---|
| id | Yes | ID of the campaign |
Changes observed during successful MCP inspections.
Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
The description declares 'Writes nothing', but the annotations set readOnlyHint=false and destructiveHint=true. A no-write preview is by definition read-only and non-destructive, so the stated behavior directly contradicts the structured safety profile and an agent could wrongly treat this as a mutating, dangerous call.
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?
Front-loaded with the one-line purpose, then the behavioral detail, then the 'Writes nothing' and access/feature prerequisites. Sentences are stacked in priority order with no filler.
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 tool with no output schema, the description covers recipient selection, validation behavior, and prerequisites well. The main gap is the unreconciled safety profile, which is more an annotation problem than a description omission.
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 100% for the single 'id' parameter, so the schema already carries the parameter semantics. The description adds no format/source detail beyond 'campaign', so the 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+resource ('Preview a campaign's message') and goes beyond the title to explain what previewing actually entails: validating template/variable mapping and rendering placeholders for up to three recipients. It is clear against generic siblings like get_whatsapp_campaign, but it never differentiates itself from the very close sibling preview_whatsapp_campaign_audience, which is the pairing an agent most needs disambiguated.
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 when previewing is useful (before sending, to verify template and mapping) and the recipient-selection rule, but it offers no explicit when-to-use/when-not guidance and does not name the adjacent alternatives (preview_whatsapp_campaign_audience, get_whatsapp_campaign). Usage must be inferred.
Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.
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