Reference · MCP methods

MCP method registry

nci-mcp registers exactly two tools and three resources. There are no other methods, no admin tools, no hidden helpers — the table below is the complete surface.

Tools

Tool	Schema	Returns
`nci_query`	Discriminated union over `subcommand`: `find`, `symbol`, `show`, `snippet`, `overloads`, `packages`, `package_versions`, `package_deps`, `source_packages`, `active_package`, `symbols`, `evidence`. Optional `database` overrides the resolved DB path.	CLI envelope `{ok:true, data:…, meta:…}` on success, `{ok:false, error:…}` on failure.
`nci_sql`	Optional `database`, `schema`, `command`, `sql_parts`, `max_rows` (default `500` when not in schema mode), `format` (`json` default, `jsonl`, `plain`). At least one of `schema:true`, `command`, or `sql_parts` is required. When `schema` is true, the MCP does not pass `--max-rows` (DDL-only path).	Raw row array (no envelope). `--max-rows` failures surface as MCP errors.

The full input schemas live in packages/nci-mcp/src/nci-query.ts and nci-sql.ts and are exported as zod schemas — read those files when a client wants the canonical shape.

Resources

URI	Mime	What it returns
`nci://primer/agent`	`text/markdown`	Compact NCI-first workflow primer. Same text shown at /docs/primer.
`nci://primer/reference`	`text/markdown`	Tabular schema reference: tables, columns, joins, edge cases.
`nci://database/active`	`application/json`	Read-only snapshot from `nci db status --format json` — path, size, `schema_version`, `indexer_output_revision`, `engine_version`. Strictly informational.

Server identity

The MCP server announces itself as name: "nci-mcp" with a version that matches its npm package version. The server’s instructions string (set in packages/nci-mcp/src/index.ts) tells the agent to read nci://primer/agent first — the same advice rendered at Agent primer.