send16-mcp

create_webhook

Register an outgoing webhook endpoint to receive event notifications. Send16 sends POST requests with event JSON and HMAC-SHA256 signature to the specified URL.

Instructions

Register an outgoing webhook endpoint. Send16 POSTs event JSON to this URL with an HMAC-SHA256 signature. Outgoing webhooks are a plan feature.

Tool call template

Replace each placeholder with a value matching the input schema. Only required parameters are included; add optional parameters as needed.

{
  "id": 1,
  "jsonrpc": "2.0",
  "method": "tools/call",
  "params": {
    "arguments": {
      "name": "<name>",
      "url": "<url>",
      "events": "<events>"
    },
    "name": "create_webhook"
  }
}

Input Schema

Name	Required	Description
`url`	Yes	HTTPS endpoint to receive events
`name`	Yes	A label for this endpoint
`apiKey`	No	Send16 API key (overrides SEND16_API_KEY env var)
`events`	Yes	Event types to subscribe to
`enabled`	No	Whether the endpoint is active (default true)

Schema Changelog

Changes observed during successful MCP inspections.

First observedv0.5.7Jul 11, 2026

TDQS

B3.3/5.0

Behavior2/5

Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?

No annotations provided. Description mentions HMAC-SHA256 signature but omits side effects, permissions, or idempotency. Minimal behavioral disclosure for a creation operation.

Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.

Conciseness4/5

Is the description appropriately sized, front-loaded, and free of redundancy?

Two concise sentences, no fluff. Slight clarity issue: 'Send16' likely a typo for 'Sends' or 'Send 16'.

Shorter descriptions cost fewer tokens and are easier for agents to parse. Every sentence should earn its place.

Completeness2/5

Given the tool's complexity, does the description cover enough for an agent to succeed on first attempt?

No output schema. Description does not explain return value (e.g., webhook ID, secret). Lacks critical info for a creation tool.

Complex tools with many parameters or behaviors need more documentation. Simple tools need less. This dimension scales expectations accordingly.

Parameters3/5

Does the description clarify parameter syntax, constraints, interactions, or defaults beyond what the schema provides?

Schema covers all 5 parameters with descriptions. The description adds no new parameter info, so baseline 3 applies.

Input schemas describe structure but not intent. Descriptions should explain non-obvious parameter relationships and valid value ranges.

Purpose5/5

Does the description clearly state what the tool does and how it differs from similar tools?

'Register an outgoing webhook endpoint' clearly states the verb and resource. Distinguishes from sibling tools like list_webhooks, delete_webhook.

Agents choose between tools based on descriptions. A clear purpose with a specific verb and resource helps agents select the right tool.

Usage Guidelines3/5

Does the description explain when to use this tool, when not to, or what alternatives exist?

No explicit when-to-use or alternatives. The phrase 'Outgoing webhooks are a plan feature' hints at prerequisites but lacks actionable guidance.

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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