List A/B tests with per-variant results and whether a winner has been selected yet.
| Name | Required | Description | Default |
|---|---|---|---|
| page | No | Page number (default 1) | |
| type | No | Filter by test source: 'campaign' for campaign A/B tests (subject/content/send_time/from_name variants on a campaign), 'subject' for standalone subject-line tests | |
| limit | No | Results per page (default 20) |
Changes observed during successful MCP inspections.
Input schema / properties / type / descriptionPrevious value: -"Filter by what is being tested"New value: +"Filter by test source: 'campaign' for campaign A/B tests (subject/content/send_time/from_name variants on a campaign), 'subject' for standalone subject-line tests"Input schema / properties / type / enumPrevious value: -[
- "subject",
- "content",
- "send_time",
- "from_name"
-]New value: +[
+ "campaign",
+ "subject"
+]Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
Annotations already declare readOnlyHint, idempotentHint, and non-destructive behavior, so the safety profile is covered. The description adds useful output context (per-variant results, winner status) but says nothing about pagination behavior, ordering, or what an unselected test looks like.
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 before the return-content detail. No filler, though it is sparse enough that more useful context could have been added at little cost.
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 read-only, no-required-parameter list tool whose annotations cover the safety profile and whose schema fully documents all three parameters, the description is sufficient. It hints at the returned fields and there is no output schema requiring separate explanation.
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%, with the type enum and its campaign/subject semantics fully documented in the schema itself. The description adds no parameter meaning beyond what the schema already provides, so the baseline 3 applies.
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 specific verb and resource (list A/B tests) and adds what the listing contains: per-variant results and winner-selection status. It is clearly distinguishable from the write-side siblings create_ab_test and select_ab_test_winner, though it does not explicitly name them.
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?
There is no guidance on when to use this tool versus alternatives, no prerequisites, and no exclusions. The only usage signal is the imperative 'List', and the agent must infer that this is the read counterpart to create_ab_test/select_ab_test_winner.
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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