set_default_email_senderMake a sender the account default.
| Name | Required | Description | Default |
|---|---|---|---|
| id | Yes | Sender ID (from list_email_senders) |
| Name | Required | Description | Default |
|---|---|---|---|
| data | No | The sender, now the account default — every send that names no sender_id uses it. | |
| success | Yes | True when the call succeeded. A failure comes back as an error result instead. |
Changes observed during successful MCP inspections.
Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
Annotations only indicate non-readOnly and non-destructive, which is minimal. The description adds no further behavioral details, such as whether the previous default sender is overwritten, whether verification is required, or any side effects. For a mutation tool, this is insufficient disclosure.
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, efficient sentence with no filler words. The core action is front-loaded, making it immediately parseable. Perfectly concise for a simple operation.
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 setter with one parameter and an output schema, the description is minimally adequate. However, it omits any error-handling context (e.g., behavior when the sender ID is invalid) or confirmation of the change. Given the tool's mutation nature, a bit more context would improve completeness, but it is not severely lacking.
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 covers the single parameter 'id' with a clear description ('Sender ID (from list_email_senders)'), providing 100% coverage. The tool description adds no extra semantic meaning beyond what the schema already offers, so a 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 'Make a sender the account default' clearly states the action (make), the resource (sender), and the scope (account default). It is specific and distinguishes from siblings like set_default_email_template, which targets a different resource. The tool name reinforces the email-sender context.
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 versus alternatives. There is no mention of prerequisites, such as the sender needing to exist or be verified, nor any contrast with similar operations like set_email_provider. The agent is left to infer context from the name alone.
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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