The 3ngram MCP server exposes the following introspection tools.
Every entry is generated from the tool’s source signature and docstring,
so this page never drifts from the backend.
Required parameters are marked with the required attribute. Optional
parameters show their default value.
list_sources
List Indexed Sources · read-only · non-destructive · idempotent · closed-world
List indexed content sources with per-source chunk counts.
Call this before search whenever you’re unsure which repos or paths
are actually indexed for the current user. The response lets you branch
honestly: if no source matches the repo you expected, don’t keep
broadening the search — tell the user the content isn’t indexed.
Returns a dict shaped as :class:ListSourcesResponse:
{sources: [SourceInfo], total: int}. Each SourceInfo carries
source_id, source_type, path_or_repo, chunks,
last_synced, status and (for GitHub sources) branch +
error_message.
Returns: dict[str, Any]
Source: backend/src/engram/mcp/tools/introspection.py
This tool takes no parameters. 
