accelo-mcp

An unofficial Model Context Protocol server for the Accelo CRM platform. It exposes Accelo data and operations to MCP-compatible AI assistants through the documented Accelo REST API.

This project is not affiliated with or endorsed by Accelo. Users are responsible for their Accelo account, OAuth application, permissions, and data handling.

Installation

With uvx

The recommended installation for MCP hosts is:

{
  "mcpServers": {
    "accelo": {
      "command": "uvx",
      "args": ["accelo-mcp"],
      "env": {
        "ACCELO_DEPLOYMENT": "your-deployment",
        "ACCELO_CLIENT_ID": "your-client-id",
        "ACCELO_CLIENT_SECRET": "your-client-secret"
      }
    }
  }
}

To pin a release:

"args": ["accelo-mcp==0.1.0"]

uvx installs the package into an isolated environment and runs the accelo-mcp command.

With pip

python3 -m pip install accelo-mcp
accelo-mcp

From source

git clone <repository-url>
cd accelo-mcp
python3 -m venv .venv
source .venv/bin/activate
pip install -e ".[dev]"

Configuration

Copy .env.example to .env, or provide these variables through the MCP host:

Variable	Required	Default	Description
ACCELO_DEPLOYMENT	Yes	—	Deployment prefix, such as example for example.accelo.com
ACCELO_CLIENT_ID	Yes	—	OAuth2 client ID from an Accelo application
ACCELO_CLIENT_SECRET	Depends on auth type	—	OAuth2 client secret; not required for public PKCE applications
ACCELO_AUTH_TYPE	No	web	web, service, installed, or public
ACCELO_SCOPE	No	read(all)	OAuth2 scope; defaults to read-only. Add write access explicitly, e.g. read(all),write(all), only if you need the write tools
ACCELO_REDIRECT_URI	For web and public	http://localhost:9876/callback (web only)	Local OAuth callback URL. Optional for web (defaults as shown); required for public with no default. Must exactly match the redirect URI registered on the Accelo application.

HTTP transport variables (used only with --http or --sse):

Single-user scope. The HTTP / SSE transports have no inbound authentication and act with one shared Accelo identity for every caller. This server is for a single operator; when running over HTTP it is your responsibility to ensure only the one intended user can reach it. See the fuller note under Usage and SECURITY.md.

The boolean variables accept 1/true/yes/on or 0/false/no/off (case-insensitive). To use a default, leave the line unset (not blank); a present-but-blank value is rejected at startup. The Applies to column shows which transport consumes each variable — --http only variables are ignored under --sse.

Variable	Default	Applies to	Description
ACCELO_MCP_HOST	127.0.0.1	--http, --sse	Interface to bind. 127.0.0.1 keeps it local-only (recommended). Only set 0.0.0.0 inside a container, and publish the port to loopback on the host — see the single-user scope note above and SECURITY.md.
ACCELO_MCP_PORT	3000	--http, --sse	TCP port to listen on.
ACCELO_MCP_PATH	/mcp	--http only	Streamable HTTP endpoint path. Must start with /; a value without a leading slash is rejected at startup. SSE does not use a configurable path.
ACCELO_MCP_JSON_RESPONSE	false	--http only	Return a single JSON response instead of an SSE stream.
ACCELO_MCP_STATELESS	false	--http only	Run without per-session MCP protocol state. This only affects the transport-level session the MCP library tracks; it does not add per-user credentials — every request still uses the one shared Accelo identity (see the single-user scope note above).
ACCELO_MCP_ALLOWED_HOSTS	—	--http, --sse	Comma-separated Host header allow-list for DNS-rebinding protection. Matching is exact unless an entry ends in :*, and clients send the bound port, so use the host:* form — e.g. 127.0.0.1:*,localhost:* for a loopback-published container, or your-host:* behind a proxy. Required when the server is reached through any hostname other than localhost. A non-standard loopback bind also needs it: e.g. ACCELO_MCP_HOST=127.0.0.5 fails closed (every request 421) unless you set ACCELO_MCP_ALLOWED_HOSTS=127.0.0.5:*.
ACCELO_MCP_ALLOWED_ORIGINS	—	--http, --sse	Comma-separated Origin header allow-list.
ACCELO_MCP_DISABLE_DNS_REBINDING_PROTECTION	false	--http, --sse	Disable the Host/Origin check entirely. Prefer setting the allow-lists above instead. On a non-loopback bind, this is the explicit override that lets the server start with no allow-list (otherwise it refuses — see below).
ACCELO_MCP_ALLOW_UNAUTHENTICATED	false	--http, --sse	Acknowledge that the HTTP transport has no inbound authentication. Required to start on a non-loopback bind (e.g. 0.0.0.0); the server refuses to start on a non-loopback host without it, to prevent accidental exposure. On a non-loopback bind the server also requires ACCELO_MCP_ALLOWED_HOSTS (an Origin allow-list alone does not close the DNS-rebinding gap) — or an explicit ACCELO_MCP_DISABLE_DNS_REBINDING_PROTECTION=true — otherwise it refuses. See SECURITY.md.

Create or obtain an OAuth application for the Accelo deployment you intend to access. Never commit client secrets, refresh tokens, access tokens, cookies, or webhook secrets.

Authentication types

All four authentication types use OAuth 2.0. They differ in whether a person authorises interactively in a browser and whether a client secret is required.

Auth type	OAuth 2.0 grant	Interactive browser login	Client secret	Typical use
web	Authorisation Code + refresh token	Yes, once	Required	Individual users; the recommended default
public	Authorisation Code with PKCE + refresh token	Yes, once	Not required	Publicly distributed clients that cannot keep a secret
installed	Authorisation Code via PIN + refresh token	Yes (approve, then enter a PIN)	Required	Installed clients using Accelo's PIN approval
service	Client Credentials	No	Required	Server-to-server automation under a shared service identity

Key points:

• public still requires OAuth. "Public" means no client secret is distributed, not that authentication is skipped. On first run the server opens your browser, you log in to Accelo and authorise, Accelo redirects back to a local 127.0.0.1 callback listener, and the server exchanges the authorisation code (using a PKCE code_verifier) for tokens. No client secret is ever sent.
• service is the only non-interactive flow. It authenticates as a service identity via the Client Credentials grant and never opens a browser. Every other type requires a one-time interactive authorisation.
• After the first authorisation, web, public, and installed cache a refresh token and reauthorise silently, so the browser step is not repeated on later runs.
• The redirect URI must line up in three places for web and public: the ACCELO_REDIRECT_URI you set, the port the local callback listener binds (derived from that URI, or 8080 if the URI has no explicit port), and the redirect URI registered on the Accelo application. Accelo rejects the authorisation request if its registered value does not match. For public, ACCELO_REDIRECT_URI is mandatory and has no default.

Tokens are cached locally at ~/.accelo-mcp/tokens.json with restrictive file permissions. The local callback listener binds to 127.0.0.1 only.

Usage

The default transport is stdio, which is suitable for Claude Desktop, Kiro, and other local MCP hosts:

accelo-mcp

For remote or networked hosts, run the server over Streamable HTTP (the current MCP HTTP transport):

accelo-mcp --http

This listens on http://127.0.0.1:3000/mcp by default.

The transport is chosen by a single flag: --http (or its alias --streamable-http) for Streamable HTTP, --sse for the deprecated SSE transport, and no flag for the default stdio transport. The flags are mutually exclusive — passing a conflicting pair (e.g. --sse --http), an unknown flag, or a stray argument exits non-zero with a usage message. Run accelo-mcp --help for the full usage.

When running over HTTP (or SSE), GET /healthz returns 200 with {"status": "ok"} for liveness probes. It is a sibling route that is not behind the Host/Origin allow-list, so a load balancer can probe it by instance IP even when the DNS-rebinding allow-list would reject /mcp for that Host. It takes no credentials, performs no Accelo call, and returns no secrets.

Single-user scope. This server has no inbound authentication and acts with one shared Accelo identity for every caller (see SECURITY.md). It is intended for a single operator. When running over HTTP, it is your responsibility to ensure only the one intended user can reach it — keep the bind on loopback, or restrict network access to that single client and set the Host/Origin allow-lists below. Do not expose the HTTP transport to an untrusted network.

If you must serve from inside a container or behind a reverse proxy, bind beyond loopback only behind a network restriction that admits the single permitted client, and allow-list the expected hostname so DNS-rebinding protection stays active and does not reject proxied requests:

# Publish the container port to loopback on the host, not to all interfaces:
#   docker run -p 127.0.0.1:8080:8080 ...
# The allow-list below assumes a host-side reverse proxy that forwards with
# Host: mcp.internal.example; the 127.0.0.1:* / localhost:* entries keep a
# direct loopback request working (a custom allow-list REPLACES the library's
# loopback defaults, and matching is exact unless an entry ends in ":*").
ACCELO_MCP_HOST=0.0.0.0 \
ACCELO_MCP_PORT=8080 \
ACCELO_MCP_ALLOWED_HOSTS=mcp.internal.example,127.0.0.1:*,localhost:* \
ACCELO_MCP_ALLOWED_ORIGINS=https://mcp.internal.example \
ACCELO_MCP_ALLOW_UNAUTHENTICATED=true \
accelo-mcp --http

The server refuses to start on a non-loopback host unless you set ACCELO_MCP_ALLOW_UNAUTHENTICATED=true, acknowledging that it has no inbound authentication. This stops accidental exposure (an empty ACCELO_MCP_HOST= value or a copied example); it does not block an intended exposed bind — you opt in explicitly. On a non-loopback bind the server also requires a Host/Origin allow-list (ACCELO_MCP_ALLOWED_HOSTS/ACCELO_MCP_ALLOWED_ORIGINS), as in the example above — without one it refuses, because DNS-rebinding protection would otherwise be off and the permitted user's browser becomes an attack vector. If you truly want no Host/Origin check, set ACCELO_MCP_DISABLE_DNS_REBINDING_PROTECTION=true explicitly. Here ACCELO_MCP_HOST=0.0.0.0 only binds all interfaces inside the container; the -p 127.0.0.1:8080:8080 publish is what keeps it reachable only from the host. An IP restriction alone does not stop DNS-rebinding, so keep the Host/Origin allow-list set regardless.

ACCELO_MCP_STATELESS=true runs the transport without per-session MCP protocol state. This only affects the protocol-level session the MCP library tracks for stream resumption; it does not add per-user credentials or make the server multi-user — every request still uses the same single Accelo identity, so the single-user scope in SECURITY.md still applies.

The older SSE transport is still available but deprecated; prefer --http for new deployments:

accelo-mcp --sse

The server provides 219 tools covering companies, contacts, affiliations, activities, projects, tickets, tasks, retainers, sales, billing, time tracking, custom fields, resources, workflow progressions, and related Accelo objects.

For complex queries, call accelo_get_context first. It describes the Accelo object model, relationships, filtering conventions, pagination, and field selection syntax.

Filtering and field selection

All list tools accept structured filters:

{"standing": "active"}
{"date_created_after": 1690000000}
{"status": [1, 2, 3]}
{"order_by_desc": "date_modified"}

Request linked or optional fields with fields:

website,phone
postal_address(city,state)
_ALL

Development

make install  # install the package and development dependencies
make test     # run tests
make lint     # run Ruff checks
make audit    # audit Python dependencies for known vulnerabilities
make check    # run lint, tests, and dependency audit
make build    # build a wheel and source distribution

Releasing

Releases are driven by the version in pyproject.toml. Bumping that version on main is the only manual step; validation, tagging, the GitHub Release, and the PyPI publish are automated by a single workflow.

1. Bump version in pyproject.toml (for example 0.1.0 to 0.2.0) on a branch and merge it to main through a pull request. Follow semantic versioning.

2. On merge, the Release workflow (.github/workflows/publish.yml) detects the changed version and, in one run:

   • runs make check (lint, tests, and dependency audit),
   • creates the matching v<version> tag and a GitHub Release with generated notes, and
   • builds the wheel and source distribution and publishes them to PyPI via OIDC Trusted Publishing (no stored API token).

   The workflow is idempotent: if the version is unchanged since the previous commit, or the tag already exists on the remote, it does nothing.

Tagging and publishing live in the same workflow on purpose. A tag pushed by the built-in GITHUB_TOKEN does not trigger a second workflow, so a separate tag-triggered publish job would never run. Folding both into one push-triggered workflow avoids that loop-guard.

To cut a release by hand, bump the version and push the tag yourself:

git tag v0.2.0   # must equal "v" + the pyproject.toml version
git push origin v0.2.0

Note that a hand-pushed tag alone does not publish (nothing is triggered by a tag push); publishing happens through the version bump on main. The Release workflow still verifies the tag equals v + the pyproject.toml version and fails if they differ, so the tag and the package version cannot drift.

Publishing to PyPI requires a configured pypi GitHub environment and a PyPI Trusted Publisher registered for this repository's publish.yml workflow. The workflow file must stay named publish.yml: PyPI matches the trusted publisher on the exact workflow filename, so renaming it breaks publishing even though the workflow's display name is "Release".

Security

Please report suspected vulnerabilities privately. See SECURITY.md for the reporting process. Do not include credentials, customer data, or access tokens in an issue.

License

MIT. See LICENSE.