reactome-db-mcp
Click on "Deploy Server".
Wait a few minutes for the server to deploy. Once ready, it will show a "Started" state.
In the chat, type
@followed by the MCP server name and your instructions, e.g., "@reactome-db-mcp list child events of R-HSA-69278"
That's it! The server will respond to your query, and you can continue using it as needed.
Here is a step-by-step guide with screenshots.
reactome-db-mcp
An MCP server that gives coding agents direct SQL access to a locally hosted Reactome database — schema discovery, a guarded read-only
query(), and ergonomic helpers over the full GKB relational schema, all from the chat.
Built with the official Python MCP SDK (FastMCP) over stdio. It talks straight to MySQL with pure-Python PyMySQL (run via asyncio.to_thread), so there is no build toolchain to install.
reactome-db-mcp vs reactome-mcp
They are complementary — register both:
|
| |
Backend | Reactome REST + Analysis web services | local |
Needs | internet; zero setup | the local DB up (MySQL + dump loaded) |
Strength | curated, pre-joined objects; enrichment p-values/FDR; always current | fast, arbitrary joins + reverse navigation over the raw 242-table schema |
Use it for | "what does Reactome say about X", enrichment | bespoke relational queries the REST API never exposed |
Tool names are deliberately distinct (get_object vs get_entry, search_by_name vs search, …) so both can be registered without ambiguity.
Prerequisites — the local database
This server needs a running MySQL with the Reactome gk_current dump loaded as reactome_local, reachable by a read-only user. On this machine that is already set up:
MySQL 9.6 (Homebrew), database
reactome_local(~990 MB, 242 MyISAM tables, Reactome release 96).Read-only user
ro_user@localhost, empty password,SELECT-only.
If mysqld isn't running (it is not registered with brew services, so it won't survive a reboot):
brew services start mysql # reliable auto-start, or: /opt/homebrew/opt/mysql/bin/mysqld_safe &To rebuild the DB from scratch, see ../reactome_local_build (keeps gk_current.sql.gz).
Related MCP server: mysql-mcp-server
Quickstart
Requires uv (which manages Python ≥ 3.12 for you).
cd reactome-db-mcp
uv sync # install runtime deps (mcp, PyMySQL)
uv run reactome-db-mcp # boots the server on stdio (Ctrl+C to exit)Then register it with your agent (below) and ask something like:
"Using the reactome-db tools, look up R-HSA-69278, then list its child events in order."
Register with your agent
Standard stdio MCP server launched with uv run reactome-db-mcp. Run from inside the cloned directory.
Claude Code
claude mcp add reactome-db -- uv --directory "$PWD" run reactome-db-mcpCodex
codex mcp add reactome-db -- uv --directory "$PWD" run reactome-db-mcpCursor / any other MCP client — point it at the same stdio command; a ready-to-edit example lives in .mcp.json:
{
"mcpServers": {
"reactome-db": {
"type": "stdio",
"command": "uv",
"args": ["run", "--directory", "/absolute/path/to/reactome-db-mcp", "reactome-db-mcp"],
"env": { "REACTOME_DB_NAME": "reactome_local" }
}
}
}Tools
All tools are async and return JSON-shaped dicts, degrading to {"error": ...} rather than raising on bad input or a down database.
Schema discovery
Tool | Signature | Purpose |
|
| Primer on the class-table-inheritance model + key joins + data release. Read first. Also the |
|
| Tables with exact row counts + engine; |
|
| Columns of a table: type, nullability, key, default. |
Guarded raw SQL
Tool | Signature | Purpose |
|
| Run one read-only statement ( |
Ergonomic helpers (sugar over the common joins)
Tool | Signature | Purpose |
|
| Assemble a full object (stable id or DB_ID) across its inheritance chain. |
|
|
|
|
| Ordered child events of a pathway (via |
|
| Inputs / outputs / catalysts of a reaction-like event. |
|
| Reverse lookup — which objects point at this one (curated/best-effort). |
Design notes
Read-only by construction. The connection is a
SELECT-only user (writes fail at the server), PyMySQL rejects stacked statements by default, andquery()additionally checks that the statement is a single read. The string check is for clear errors, not as the security boundary — the grant is.Stable ids vs DB_IDs. Helpers accept either
R-HSA-69278or the numericDB_ID. The'R-HSA-...'text lives inStableIdentifier, joined viaDatabaseObject.stableIdentifier.Size-guarded. Every result is row-capped (
max_rows, hard ceiling 5000) and long text cells are truncated;truncatedflags either.Point-in-time data. This is a dump (release reported by
schema_overview). For the always-current Reactome, use the siblingreactome-mcp.
Configuration (env vars)
Var | Default | Meaning |
|
| MySQL endpoint |
|
| credentials |
|
| database |
|
| max pooled connections |
|
| default row cap |
|
| per-query timeout |
|
| per-cell text cap |
Example prompts
Lookup + drill-down — "Look up R-HSA-69278 with the reactome-db tools and list its child events in order."
Raw SQL — "Run
SELECT _class, COUNT(*) FROM DatabaseObject GROUP BY _class ORDER BY 2 DESC LIMIT 10and summarize."Reverse navigation — "Which pathways and reactions reference the object named 'CYCB:CDK1'? Use get_referrers."
Schema spelunking — "Call schema_overview, then describe the Pathway and Pathway_2_hasEvent tables."
Development
uv sync --extra dev # pytest, pytest-asyncio
uv run pytest # safety-layer suite runs fully offline (no DB)
# opt-in live-DB integration tests (needs reactome_local up):
REACTOME_DB_MCP_INTEGRATION=1 uv run pytestSmoke-test the live server:
uv run reactome-db-mcp # console script
uv run python -m reactome_db_mcp # module entry point
uv run python server.py # source-checkout shim
uv run mcp dev src/reactome_db_mcp/server.py # MCP Inspector dev UIreactome-db-mcp/
├── src/reactome_db_mcp/
│ ├── server.py # FastMCP app, lifespan pool, all tools + resource
│ ├── db.py # PyMySQL pool + read-only safety layer (pure, tested)
│ └── schema.py # curated schema primer + class-inheritance map
├── server.py # source-checkout compatibility shim
├── tests/ # offline safety-layer suite + opt-in DB integration tests
├── pyproject.toml # uv-managed project
├── .mcp.json # example stdio MCP config
└── PLAN.md # design & build record (verified 2026-06-22)Acknowledgements
Powered by Reactome, a free, open-source, open-access, curated and peer-reviewed pathway database. Please cite Reactome when publishing work that uses this data — see https://reactome.org/cite.
This project is not affiliated with or endorsed by the Reactome team.
License
MIT © Tien Comlekoglu
Available Tools
9 toolsdescribe_tableA
Show the columns of a table: name, type, nullability, key, default, extra.
Args:
table: Exact table name (see `list_tables`). e.g. "Pathway",
"Pathway_2_hasEvent", "DatabaseObject".
Returns:
Dict `{table, columns: [{name, type, nullable, key, default, extra}]}`.
Inputs: table (required).
get_objectA
Fetch a full Reactome object, assembled across its inheritance chain.
Resolves a stable id ('R-HSA-69278') or numeric `DB_ID`, then merges the
`DatabaseObject` core fields with the subclass-table attributes that share
the same `DB_ID` (e.g. a Pathway pulls in `Event` + `Pathway` columns).
Args:
id: An 'R-HSA-...' stable id or a numeric DB_ID.
Returns:
Dict `{DB_ID, _class, _displayName, stable_id, attributes: {...}}` where
`attributes` is the union of the subclass rows (leaf class wins on any
name clash). `{"error": ...}` if the id is unknown.
Inputs: id (required).
get_participantsA
Get the inputs, outputs, and catalysts of a reaction-like event.
Args:
id: A ReactionlikeEvent (Reaction/BlackBoxEvent/...) stable id or DB_ID.
Returns:
Dict `{reaction_DB_ID, inputs, outputs, catalysts}` where `inputs`/
`outputs` are physical-entity dicts and each `catalysts` entry also
carries `catalyst_activity_DB_ID` and the GO `activity` DB_ID. Empty
lists if the object isn't a reaction or has none.
Inputs: id (required).
get_pathway_eventsA
List the ordered child events (sub-pathways & reactions) of a pathway.
Args:
id: A Pathway stable id ('R-HSA-69278') or numeric DB_ID.
Returns:
Dict `{pathway_DB_ID, count, events: [{rank, DB_ID, _class,
_displayName, stable_id}], truncated}`, ordered by `hasEvent_rank`.
Inputs: id (required).
get_referrersA
Reverse lookup: which objects point AT this one (the inverse navigation REST makes awkward).
Scans a curated set of common containment relations — which pathways contain
this event, which complexes/sets contain this entity, which reactions consume
or produce it. **Best-effort, not exhaustive** (the schema has 132 link
tables; this checks the high-value ones).
Args:
id: A stable id or numeric DB_ID of the object being referred to.
attribute: Optionally restrict to one relationship label
(contained_in_pathway, component_of_complex, member_of_set,
input_to_reaction, output_of_reaction).
limit: Max referrers per relation (1-500, default 50).
Returns:
Dict `{object_DB_ID, referrers: [{relationship, via_table, DB_ID, _class,
_displayName, stable_id}], scanned, note}`.
Inputs: id (required), attribute, limit.
list_tablesA
List tables in the database with their (exact) row counts and engine.
Args:
filter: If given, only tables whose name contains this substring
(case-insensitive). e.g. "_2_" for link tables, "Reference" for
reference-data tables.
limit: Max tables to return (default 500; the DB has 242).
Returns:
Dict `{count, tables: [{table, rows, engine}], truncated}`, ordered by
row count descending. Row counts are exact (all tables are MyISAM).
Inputs: filter, limit.
queryA
Run a single READ-ONLY SQL statement against the Reactome DB.
Accepts one `SELECT` / `WITH` / `SHOW` / `DESCRIBE` / `EXPLAIN` statement.
Writes are impossible (the connection is a SELECT-only user) and multiple
statements are rejected. If a `SELECT`/`WITH` has no `LIMIT`, one is injected
automatically. Call `schema_overview` first to learn the join patterns.
Args:
sql: The statement to run. Use parameter-free SQL; quote literals
normally. e.g. `SELECT d.DB_ID, d._displayName FROM DatabaseObject d
JOIN StableIdentifier si ON d.stableIdentifier = si.DB_ID
WHERE si.identifier = 'R-HSA-69278'`.
max_rows: Max rows to return (1-5000, default 200). Long text cells are
also truncated; `truncated` flags either kind.
Returns:
Dict `{columns, rows, row_count, truncated, sql}` where `rows` is a list
of lists aligned to `columns`, and `sql` is the statement actually run
(with any auto-injected LIMIT). On a bad statement or DB error, returns
`{"error": ...}`.
Inputs: sql (required), max_rows.
schema_overviewA
Explain the Reactome GKB schema so you can write correct SQL.
Returns a primer on the class-table-inheritance model (the `DatabaseObject`
supertable, subclass tables sharing `DB_ID`, the `Class_2_attribute` link
tables, and the stable-id join), the most useful tables, key join recipes,
and the data release loaded. **Read this once before writing `query()` SQL.**
The same primer is also available as the `schema://reactome` MCP resource.
Inputs: no named parameters.
search_by_nameA
Search objects by _displayName.
Args:
query: Text to look for in the display name.
classes: Optional `_class` filter, e.g. ["Pathway", "Reaction"].
limit: Max results (1-200, default 25).
anchored: If True, match `name LIKE 'query%'` (fast — uses the prefix
index). If False (default), match `'%query%'` — more thorough but a
full scan of the 1.86M-row supertable (~1-2s). There are no FULLTEXT
indexes, so prefer `anchored=True` and/or a `classes` filter for hot
paths.
Returns:
Dict `{count, anchored, results: [{DB_ID, _class, _displayName, stable_id}]}`.
Inputs: query (required), classes, limit, anchored.
Tool Schema Changelog
Recent tool additions, removals, and schema changes observed during successful MCP inspections.
Loading tool schema changelog…
TDQS
Scored across 9 tools
Each tool has a distinct purpose: schema exploration (list_tables, describe_table, schema_overview), object retrieval (get_object, search_by_name), relationship queries (get_participants, get_pathway_events, get_referrers), and raw SQL (query). No overlapping functionality.
Most tools follow a consistent verb_noun pattern (e.g., describe_table, get_object, list_tables). However, 'query' and 'schema_overview' are outliers—'query' is a bare verb and 'schema_overview' is noun_noun—but the overall pattern is mostly adhered to.
With 9 tools, the server is well-scoped for a biological database MCP server. It provides essential operations without bloat, covering schema exploration, object retrieval, relationship navigation, and custom queries.
The tool set covers the primary interactions with Reactome: exploring schema, fetching objects, searching by name, retrieving participants and pathway events, reverse lookups, and arbitrary SQL queries. No obvious gaps for typical workflows.
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