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. |
Changes observed during successful MCP inspections.
Input schema / $schemaRemoved value: -"http://json-schema.org/draft-07/schema#"Output schema / $schemaRemoved value: -"http://json-schema.org/draft-07/schema#"Output schema / properties / success / descriptionPrevious value: -"True when the call succeeded. A failure comes back as an error result instead."New value: +"True when the call succeeded."Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
Annotations declare readOnlyHint=false and destructiveHint=false, which is consistent with the description's implied mutation without destructive impact. The description adds no extra behavioral details beyond the annotations, but it doesn't contradict them either. Given the annotations carry the safety profile, a neutral score is appropriate.
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, clear sentence with zero filler. It front-loads the action and outcome efficiently, making it easy for an agent to parse quickly.
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 one-parameter operation with an output schema and annotations, the description is sufficient. It clearly states the intent. While it could elaborate on the effect of setting a default (e.g., influencing future email sends), the low complexity and available schema/annotations keep the bar low, and nothing essential is missing for correct invocation.
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 description coverage is 100%—the only parameter, 'id', is described as 'Sender ID (from list_email_senders)'. The description itself adds no extra meaning beyond the schema, so it meets the baseline without exceeding 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 states a clear action: 'Make a sender the account default.' It identifies the resource (sender) and the outcome (default for account). While it doesn't explicitly contrast with set_default_email_template, the distinct resource type is evident, and the verb is specific enough to separate from sibling operations.
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 is provided on when to use this tool versus alternatives. It doesn't mention that the sender ID must come from list_email_senders (though the schema hints at this) or that the default affects future email sends. There is no mention of prerequisites or exclusions, leaving the agent to infer context.
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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