Retrieve mailing lists with IDs, types, subscriber counts, and tags so you can find the list IDs needed by subscriber, campaign, and other tools.
List mailing lists with ID, type, subscriber count and tags. Use it to find the list IDs required by add_subscriber, create_campaign and other tools.
| Name | Required | Description | Default |
|---|---|---|---|
No arguments | |||
Changes observed during successful MCP inspections.
Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
readOnlyHint=true already covers the safety profile, and the description adds value by disclosing the returned fields (ID, type, subscriber count, tags) even though no output schema exists. It doesn't mention pagination or whether all lists are returned in one call, which is the remaining gap.
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 short sentences, zero waste: the first defines the output, the second gives the motivating use case. Front-loaded and easy to scan.
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 zero-param, read-only lookup with no output schema, the description covers what comes back and why to call it. Minor omissions (pagination behavior, ordering, whether filtering is possible) keep it from a 5.
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 tool takes no parameters, so there is no parameter semantics to explain; the baseline for a zero-param tool is 4. The description correctly implies the call needs no arguments.
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?
States a specific verb and resource ('List mailing lists') and enumerates what each entry contains (ID, type, subscriber count, tags). It doesn't explicitly distinguish itself from nearby readers like get_list_by_id or list_subscribers, but the 'list all lists' scope is unambiguous.
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?
Explicitly states the use case: finding list IDs needed by add_subscriber, create_campaign and others, which is exactly the precondition an agent needs. It doesn't say when to prefer get_list_by_id or get_list_subscribers_tool instead, so it stops short of full alternative routing.
Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.