Add specified contact IDs to an audience to organize your contacts for targeted email campaigns.
Add contacts (by ID) to an audience.
| Name | Required | Description | Default |
|---|---|---|---|
| apiKey | No | Send16 API key (overrides SEND16_API_KEY env var) | |
| audienceId | Yes | Audience ID | |
| contactIds | Yes | Contact IDs to add |
Changes observed during successful MCP inspections.
v0.5.7Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
With no annotations, the description carries full burden but only states the basic action. It does not disclose whether adding is idempotent, whether duplicate contact IDs are ignored, whether the audience must exist, or any side effects. Lacks behavioral context beyond the minimal description.
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?
The description is a single, clear sentence with no unnecessary words. However, it is so brief that it may be under-specified, slightly reducing conciseness value.
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?
Given no output schema, no annotations, and only 3 parameters, the description is insufficient. It does not explain what happens on success, error cases, or how the tool fits into the larger workflow (e.g., requires existing contacts).
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%, so baseline is 3. The description adds no additional meaning beyond the schema; it only restates 'by ID' which is already clear from the contactIds parameter description.
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 clearly states the action ('Add contacts') and the resource ('to an audience'), specifying that contacts are identified by ID. It distinguishes from sibling tools like 'remove_contact_from_audience' implicitly, but does not explicitly differentiate from 'import_contacts' which might also add contacts.
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 is provided on when to use this tool versus alternatives like 'import_contacts' or 'create_contact'. There is no mention of prerequisites (e.g., contacts must exist) or when to prefer this tool over others.
Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.