Ballast - Cold Email

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list_threads

List reply threads newest first, filtered by unread status, label, mailbox, or campaign, and paged with a cursor to browse an Unibox inbox.

Instructions

Reply threads, newest first Filter by unread, label, mailbox or campaign. Page with cursor from the previous answer.

Tool call template

This tool declares no required parameters. Add optional parameters from the input schema as needed.

{
  "id": 1,
  "jsonrpc": "2.0",
  "method": "tools/call",
  "params": {
    "arguments": {},
    "name": "list_threads"
  }
}

Input Schema

Name	Required	Description	Default
`view`	No		all
`cursor`	No
`search`	No	Matches the lead's email, name or company, and the subject
`labelId`	No	A label id, or "none" for threads without a label
`mailboxId`	No
`campaignId`	No

Schema Changelog

Changes observed during successful MCP inspections.

First observedv0.1.0Oct 21, 2026

TDQS

B3.4/5.0

Behavior3/5

Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?

No annotations are provided, so the description carries the full burden. It usefully discloses the sort order ('newest first') and the pagination contract ('Page with cursor from the previous answer'), but says nothing about permissions, result caps, or what a thread record contains.

Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.

Conciseness4/5

Is the description appropriately sized, front-loaded, and free of redundancy?

Two short sentences with the purpose front-loaded and no filler. The missing sentence break between 'newest first' and 'Filter' makes it read as a run-on, slightly hurting scanability.

Shorter descriptions cost fewer tokens and are easier for agents to parse. Every sentence should earn its place.

Completeness3/5

Given the tool's complexity, does the description cover enough for an agent to succeed on first attempt?

For a 6-parameter list tool with no annotations and no output schema, the description covers filtering and pagination but omits the shape of returned threads and any limits on result size. It is adequate to invoke the tool but not fully complete.

Complex tools with many parameters or behaviors need more documentation. Simple tools need less. This dimension scales expectations accordingly.

Parameters3/5

Does the description clarify parameter syntax, constraints, interactions, or defaults beyond what the schema provides?

Schema coverage is only 33% (search and labelId documented). The description partially compensates by naming four filter dimensions that map to view, labelId, mailboxId and campaignId, and it clarifies cursor usage. It does not explain the 'all' vs 'unread' enum or the 'none' label sentinel, so the compensation is incomplete.

Input schemas describe structure but not intent. Descriptions should explain non-obvious parameter relationships and valid value ranges.

Purpose4/5

Does the description clearly state what the tool does and how it differs from similar tools?

States a specific verb+resource ('Reply threads') and adds the ordering ('newest first'), which distinguishes it from the sibling get_thread (singular retrieval). It does not explicitly name any sibling, so it falls short of 5.

Agents choose between tools based on descriptions. A clear purpose with a specific verb and resource helps agents select the right tool.

Usage Guidelines3/5

Does the description explain when to use this tool, when not to, or what alternatives exist?

The filter list ('unread, label, mailbox or campaign') implies when the tool is useful, but there is no statement of when to prefer get_thread instead or any prerequisite/exclusion. Usage is inferred rather than declared.

Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.