List subscription topics to view granular categories contacts can subscribe to, enabling topic-based gating for campaigns and automations.
List subscription topics. Topics are granular categories contacts can subscribe to (e.g. 'product-updates', 'weekly-digest'). Campaigns and automations can be gated to subscribers of a specific topic.
| Name | Required | Description | Default |
|---|---|---|---|
| apiKey | No | Send16 API key (overrides SEND16_API_KEY env var) |
Changes observed during successful MCP inspections.
v0.5.7Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
No annotations provided, so description carries full burden. Only states 'List subscription topics' with no mention of side effects, permissions, rate limits, or response format. Minimal behavioral disclosure.
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 sentences, front-loaded with purpose and valuable context. No unnecessary words. Every sentence 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?
Lacks description of return values (no output schema). No information on pagination, ordering, or expected response structure. Suitable for a simple list operation but has gaps given the lack of annotations and output schema.
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 one parameter (apiKey) documented. Description adds no additional meaning beyond the schema, but baseline is 3 since schema already covers the parameter. No extra context provided.
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?
Description clearly states verb 'List' and resource 'subscription topics', and adds context about what topics are and their use in campaigns/automations. However, it does not explicitly differentiate from sibling tools like list_audiences or list_segments, though the resource name is distinct.
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?
No guidance on when to use this tool vs alternatives such as list_audiences or create_topic. The description mentions topics can gate campaigns/automations but does not state when listing is appropriate or what prerequisites exist.
Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.