Add an email address to the suppression list to block future email deliveries.
Add an email to the suppression list. Future sends to this address will be blocked.
| Name | Required | Description | Default |
|---|---|---|---|
| Yes | |||
| notes | No | ||
| apiKey | No | Send16 API key (overrides SEND16_API_KEY env var) | |
| reason | No | manual |
Changes observed during successful MCP inspections.
v0.5.7Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
Discloses the effect of blocking future sends, but lacks details on reversibility, permanence, or required permissions. Since no annotations are provided, the description carries the full burden and is only partially sufficient.
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?
Extremely concise: two sentences with no wasted words. Information is front-loaded.
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 4 parameters, no output schema, and no annotations, the description omits critical context: what happens if the email is already suppressed, how to specify a reason, and whether this is reversible. The tool's behavior is under-specified.
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 low (25%). The description does not explain the 'notes' or 'reason' parameters, leaving their purpose implicit. Only the email's role is inferred from context.
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 verb ('Add'), resource ('suppression list'), and outcome ('Future sends...blocked'). It distinguishes from siblings like 'remove_suppression' and 'list_suppressions'.
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 (e.g., remove_suppression, list_suppressions). No mention of prerequisites or exclusions.
Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.