3tears-mcp

Shared MCP (Model Context Protocol) framework. Per-product MCP servers compose this framework instead of reimplementing stdio transport, JWT auth, error mapping, and per-tool RBAC.

What's in here

Module Responsibility
server McpServer -- wraps the official mcp.server.Server. Owns tool registration, RBAC gating before handler dispatch, structured error mapping per the MCP spec.
tool McpTool dataclass (name, description, input_schema, required_permission, handler) and register_tool decorator.
http_client PlatformHttpClient -- typed httpx client with JWT login + refresh-on-401. Used by both MCP server tool handlers (calling /api/v1/...) and CLI scripts. One HTTP-client implementation, two transports.
auth Identity dataclass + IdentityProvider Protocol + EnvVarIdentityProvider (stdio impl). Authorizer Protocol + LocalGrantAuthorizer (default impl backed by McpToolGrantCollection).
rbac McpToolGrantCollection -- BaseCollection over mcp_tool_grants. Exposes the in-memory grant cache that LocalGrantAuthorizer consults.
migrations/ v01_create_mcp_tool_grants -- platform-scope DDL. Consumers register via MigrationRunner.register(epoch_pkg) (same shape as threetears.epoch).

RBAC model

Per-tool, default-deny. Each McpTool declares a required_permission string (e.g. "conversations.read", "audit.read"). On every dispatch:

  1. The framework calls Authorizer.allows(identity, required_permission).
  2. LocalGrantAuthorizer checks whether the caller's identity matches an active grant in McpToolGrantCollection for the requested permission.
  3. If denied, the framework returns a structured MCP error to the client (not a Python exception in the response body).

The configured admin identity (env-var creds in the stdio impl) is auto-granted in memory at server startup. The grant is logged but NOT written to mcp_tool_grants. This keeps the table truthful (only operator-added grants live there).

Grant changes propagate cross-pod via the mcp.rbac epoch broadcast. LocalGrantAuthorizer subscribes to Subjects.mcp_rbac_epoch() via an EpochListener; on bump it reloads the grant cache from L3. Cold-start primes from EpochClient.current(...). Missed broadcasts recover via the standard pull-on-stale path.

Identity in v1

EnvVarIdentityProvider returns one fixed Identity for the lifetime of the server, derived from env-var credentials. v2 (HTTP transport + per-call bearer-token identity) plugs in by adding a BearerTokenIdentityProvider; the rest of the framework is unchanged. The Authorizer.allows(identity, permission) interface is unchanged between v1 and v2.

Stdio transport discipline

Every byte on stdout/stderr from a stdio MCP server confuses the client. The framework configures logging to a file or to NATS; no module under threetears.mcp should write to sys.stdout / sys.stderr. An AST enforcement test guards this.

Postgres backing

CREATE TABLE IF NOT EXISTS mcp_tool_grants (
    grant_id UUID PRIMARY KEY,
    principal_type TEXT NOT NULL,   -- 'user' | 'group' | 'role'
    principal_id UUID NOT NULL,
    tool_name TEXT NOT NULL,
    permission TEXT NOT NULL,
    date_created TIMESTAMPTZ NOT NULL DEFAULT now()
);

Mutation paths (admin POST /admin/mcp/grants, DELETE /admin/mcp/grants/{id}) bump Subjects.mcp_rbac_epoch() after the row commit; sibling pods reload via the epoch listener.

Project links

Data verified by PyPI on Aug 9, 2026
Data provided by the project maintainers, verified at the time the release was uploaded to PyPI.

Key dates

PyPI data
Data sourced directly from PyPI's database.
  • Released:
Newer release available (0.35.1)

1 maintainer

PyPI data
Data sourced directly from PyPI's database.
Avatar for pace from gravatar.com pace

Credits

Author: pace

GitHub Statistics

Data verified by PyPI on Aug 9, 2026
The GitHub source repository was provided by the project maintainers and verified by PyPI at the time of upload. Stars, forks, and open issues/PRs are derived from that repository and have not been independently verified.

License expression

MIT
View SPDX License List

Requires

Python >=3.14

Classifiers

Report project as malware

Download files

Download the file for your platform. If you're not sure which to choose, learn more about installing packages.

Source Distribution

3tears_mcp-0.23.7.tar.gz (52.3 kB view details)

Uploaded Source

Built Distribution

If you're not sure about the file name format, learn more about wheel file names.

3tears_mcp-0.23.7-py3-none-any.whl (34.6 kB view details)

Uploaded Python 3

File details

Details for the file 3tears_mcp-0.23.7.tar.gz.

File metadata

  • Download URL: 3tears_mcp-0.23.7.tar.gz
  • Upload date:
  • Size: 52.3 kB
  • Tags: Source
  • Uploaded using Trusted Publishing? Yes
  • Uploaded via: twine/7.0.0 CPython/3.13.14

File hashes

Hashes for 3tears_mcp-0.23.7.tar.gz
Algorithm Hash digest
SHA256 9ca144d511a5fea15682db23c8e1178246dba9521b2c52bc14b2ed39f4ac10dc
MD5 9eaaef95908c69a71601e1e315a85db9
BLAKE2b-256 f1fa2d28af00cde9f0bdbeaf717b826d8d0d3bead5fdd40da965e82b6f834623

See more details on using hashes here.

Provenance

The following attestation bundles were made for 3tears_mcp-0.23.7.tar.gz:

Publisher: release.yml on pacepace/3tears

Attestations: Values shown here reflect the state when the release was signed and may no longer be current.

File details

Details for the file 3tears_mcp-0.23.7-py3-none-any.whl.

File metadata

  • Download URL: 3tears_mcp-0.23.7-py3-none-any.whl
  • Upload date:
  • Size: 34.6 kB
  • Tags: Python 3
  • Uploaded using Trusted Publishing? Yes
  • Uploaded via: twine/7.0.0 CPython/3.13.14

File hashes

Hashes for 3tears_mcp-0.23.7-py3-none-any.whl
Algorithm Hash digest
SHA256 2db0ad4140618e9f799844d18b2bb1098ed0f7dc94b2b6d802f053a7674cd6f4
MD5 9dd7e049fb1c78f2dc336e46ca14acb7
BLAKE2b-256 ccb96662a39fb8aa6af64964945a0d2dc2a8a2e452c5a3675a534f8f4449255a

See more details on using hashes here.

Provenance

The following attestation bundles were made for 3tears_mcp-0.23.7-py3-none-any.whl:

Publisher: release.yml on pacepace/3tears

Attestations: Values shown here reflect the state when the release was signed and may no longer be current.

Release history Release notifications | RSS feed

0.35.1

2 files

0.35.0

2 files

0.34.0

2 files

0.33.0

2 files

0.32.1

2 files

0.32.0

2 files

0.31.0

2 files

0.30.1

2 files

0.30.0

2 files

0.29.0

2 files

0.28.0

2 files

0.27.0

2 files

0.26.1

2 files

0.26.0

2 files

0.25.0

2 files

0.24.7

2 files

0.24.6

2 files

0.24.5

2 files

0.24.4

2 files

0.24.3

2 files

0.24.2

2 files

0.24.1

2 files

0.24.0

2 files

0.23.11

2 files

0.23.10

2 files

0.23.9

2 files

0.23.8

2 files

This release

0.23.7 This release

2 files

0.23.6

2 files

0.23.5

2 files

0.23.3

2 files

0.23.2

2 files

0.23.1

2 files

0.23.0

2 files

0.22.5

2 files

0.22.4

2 files

0.22.3

2 files

0.22.2

2 files

0.22.1

2 files

0.22.0

2 files

0.21.0

2 files

0.20.0

2 files

0.19.4

2 files

0.19.3

2 files

0.19.2

2 files

0.19.1

2 files

0.19.0

2 files

0.18.0

2 files

0.17.9

2 files

0.17.8

2 files

0.17.7

2 files

0.17.6

2 files

0.17.5

2 files

0.17.4

2 files

0.17.3

2 files

0.17.2

2 files

0.17.1

2 files

0.17.0

2 files

0.16.1

2 files

0.16.0

2 files

0.15.0

2 files

0.14.1

2 files

0.14.0

2 files

Anthropic, PBC Visionary sponsor Bloomberg Visionary sponsor Hudson River Trading Visionary sponsor Meta Visionary sponsor NVIDIA Visionary sponsor Microsoft Sustainability sponsor Depot Continuous Integration AWS Cloud computing and Security Sponsor Datadog Monitoring Fastly CDN Google Download Analytics Sentry Error logging StatusPage Status page