Retrieve a specific inbound or held email message by numeric ID to inspect its contents and troubleshoot delivery status.
Retrieve one inbound or held message by id.
| Name | Required | Description | Default |
|---|---|---|---|
| id | Yes | Numeric message id |
Changes observed during successful MCP inspections.
v0.2.0Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
Annotations already declare readOnlyHint=true and openWorldHint=true, covering the read-only nature and potential incomplete result sets. The description adds value by mentioning 'held' messages, which is a state that may not be obvious. However, it does not disclose error handling, response format, or any side effects, though for a read-only tool with no output schema, some of this is expected. The description does not contradict annotations.
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?
A single, efficient sentence that front-loads the verb and resource. Every word contributes to meaning, with no filler or redundant phrasing. The description is appropriately sized for a simple retrieval tool.
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 get-by-id tool with one parameter and no output schema, the description covers the basic action. However, the 'held' state is unexplained—an agent may not know what 'held' means or how it differs from a standard inbound message. There's also no context about how this tool fits into a workflow (e.g., retrieving a message before retrying or bypassing). Given the sibling tools, some additional guidance would make it more complete.
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?
The schema provides 100% coverage of the single parameter 'id' with a clear description. The tool description only refers to 'by id' without adding extra semantics (e.g., typical usage, format nuances, or relationship to message states). Baseline of 3 is appropriate when the schema fully documents the parameter and the description doesn't go beyond it.
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 (retrieve), the resource (inbound or held message), and the method (by id). It distinguishes itself from list_inbound and other siblings by specifying a single message. The term 'held' adds specificity beyond a generic 'get message'.
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 explicit guidance on when to use this tool versus alternatives. While it's implied that you use it for retrieving a single message and list_inbound for all messages, there's no mention of when not to use it, prerequisites, or how it relates to retry_inbound or bypass_inbound for held messages. The guidance is purely implicit.
Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.