list_suppressionsReturn the user's suppression list — addresses (and full domains) that shiply skips when sending. Bounces, complaints, manual user adds, and AI-detected unsubscribes all land here.
| Name | Required | Description | Default |
|---|---|---|---|
No arguments | |||
| Name | Required | Description | Default |
|---|---|---|---|
| result | Yes |
Changes observed during successful MCP inspections.
Output schema / (root)Previous value: -nullNew value: +{
+ "$schema": "http://json-schema.org/draft-07/schema#",
+ "additionalProperties": false,
+ "properties": {
+ "result": {}
+ },
+ "required": [
+ "result"
+ ],
+ "type": "object"
+}Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
Annotations already declare readOnlyHint=true. The description adds value by specifying that the list includes addresses and full domains, and categorizes the types of suppressions (bounces, complaints, manual adds, AI-detected unsubscribes). No contradictions.
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?
Two sentences, both highly informative. No filler words. The first sentence states the core function; the second adds valuable detail about the sources of suppressions. Front-loaded and efficient.
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?
Given no parameters and the presence of an output schema, the description sufficiently covers what the tool does and what kind of data it returns. It explains the purpose and scope of the suppression list completely for an agent.
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 input schema has zero parameters, so schema coverage is 100%. The description does not need to explain parameters. It adds context about the content of the returned list, which is appropriate for a parameterless tool.
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 uses a specific verb 'Return' and resource 'suppression list', clearly stating it lists emails and domains that are skipped. It enumerates the sources of suppressions (bounces, complaints, etc.), distinguishing it from siblings like add_suppression and remove_suppression.
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 when to use it (to view suppressed addresses) but does not explicitly exclude alternatives or mention when not to use it. Given sibling tools for adding/removing suppressions, context makes usage clear, but lacks explicit guidance.
Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.