Fetch a message's complete event timeline—created, sent, delivered, opened, clicked—to analyze its full lifecycle.
Fetch a single message with its full event timeline (created → sent → delivered → opened → clicked → ...).
| Name | Required | Description | Default |
|---|---|---|---|
| id | Yes | Message ID | |
| 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 are provided, so the description must fully disclose behavior. It only states that it returns the event timeline, but does not mention read-only nature, authentication requirements, rate limits, or any other side effects. This is minimal disclosure for a tool with two parameters.
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 sentence that efficiently conveys the core purpose. It is front-loaded with the verb 'Fetch'. However, it could include more contextual information without becoming verbose.
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 simple fetch tool with no output schema, the description adequately states what is returned ('full event timeline'). It is sufficient for an experienced developer but lacks details on the structure of the timeline or any error conditions.
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%, and the schema already describes both parameters adequately. The description adds no extra meaning beyond what the schema provides, so baseline score of 3 is appropriate.
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 'Fetch', the resource 'a single message', and what is included ('full event timeline'). This distinguishes it from siblings like 'list_messages' or 'get_message_events'.
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 usage for retrieving a single message with timeline but does not explicitly state when to use this tool versus alternatives like 'list_messages' or 'get_message_events'. No exclusion criteria are provided.
Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.