@gomission/mcp

Mission’s open MCP interception adapter for exact-action authority.

It has one narrow job: sit before a wrapped MCP provider, classify a proposed tool call, and hold consequential calls with an immutable Trust Graduation action binding. Low-risk calls may pass through. A chat message saying “approve” is never treated as authority.

Status: experimental beta. Apache-2.0. Zero runtime dependencies.

Prove the boundary first

Requirements: Node.js 20 or newer.

npx -y @gomission/mcp@beta demo

The command uses a fake email provider and prints one machine-readable DEMO_RESULT. It proves that:

• the consequential provider function was called zero times;
• the hold contains an exact action and input hash;
• changing the reviewed input changes the commitment;
• chat text grants no execution authority.

This proves interception, not completed authorization or production adoption. The portable grant/replay proof lives in @trust-graduation/core:

npx -y @trust-graduation/core@beta demo

The three primitives

The MCP adapter implements the pre-provider hold. It does not mint a trusted Mission Key and it cannot resume a held call. A trusted approval host and executor must validate and atomically consume the matching key. The experimental A2A continuation is published at:

https://trustgraduation.org/extensions/a2a/action-authorization/v1

MCP Hold to Exact Provider Execution

The package root exposes the stable, zero-dependency binding bridge used by an external approval host and executor:

import { providerActionFromMcpBinding } from "@gomission/mcp";
import { createProviderGate } from "@trust-graduation/core";

const gate = createProviderGate({
  store: sharedAtomicGrantStore,
  authenticateGrant: verifyApprovalIssuer,
  provider: existingProviderFunction,
  writeReceipt: durableReceiptSink
});

// Re-read the actual provider input at the final seam; never trust a preview.
const action = providerActionFromMcpBinding(
  heldReceipt.action_binding,
  actualProviderInput
);
const execution = await gate.execute({
  binding: heldReceipt.action_binding,
  approval: authenticatedMissionKey,
  action
});

The bridge verifies binding integrity and maps the intercepted identities, target, constraints, expiry, and nonce into the core executor shape. The core then re-hashes the actual provider input, authenticates and atomically consumes the Key, calls the provider, and writes result-linked evidence. Mutation or replay never reaches the provider.

For a generated adapter and objective provider-call counters:

npm install @trust-graduation/core@beta
npx trust-graduation init-adapter
npx trust-graduation conformance ./mission-gate-adapter.mjs --json

With both packages installed, the included compatibility proof is:

node node_modules/@trust-graduation/core/examples/mcp-provider-roundtrip.mjs

The MCP proxy still never resumes a held call merely because chat says "approve". This bridge is for the separately authenticated approval host and provider-bound executor.

Install for Claude Desktop

npx -y @gomission/mcp@beta install-claude

The installer inspects the existing Claude Desktop MCP configuration:

• if it finds consequential MCP servers, it selects --wrap;
• otherwise it selects --local, an advisory exact-binding demonstration;
• it never auto-selects the hosted read-only mode.

Restart Claude Desktop after installation, then verify:

npx -y @gomission/mcp@beta verify

verify probes modern MCP with server/discover and tools/list, falling back to the initialize-era protocol for older endpoints. Add --json for a machine-readable report or --no-probe to inspect configuration only.

Modes

Choose explicitly when needed:

npx -y @gomission/mcp@beta install-claude --wrap
npx -y @gomission/mcp@beta install-claude --local
npx -y @gomission/mcp@beta install-claude --remote

Useful flags:

• --workspace <path> — store local receipts in an existing workspace.
• --dry-run — print the configuration change without writing it.
• --force — create configuration even when Claude Desktop is not detected.
• --remote-url <url> — override the hosted endpoint.
• MISSION_DONT_WRAP="name1,name2" — exclude selected MCP children.

Exact hold contract

For a consequential wrapped call, the adapter writes a local receipt containing:

• action class;
• privacy-preserving local workspace identifier;
• requesting MCP child;
• target when one can be inferred;
• SHA-256 input commitment;
• one-execution constraints;
• expiry and nonce;
• SHA-256 commitment over the complete binding.

Receipts are written atomically with owner-only file permissions. The adapter never stores the raw workspace path inside the binding. A local argument summary remains in the receipt for human review, so treat the receipt directory as sensitive workspace data.

MCP compatibility

Preferred protocol: 2026-07-28.

• stateless per-request _meta with client capabilities;
• mandatory server/discover;
• one JSON-RPC message per HTTP POST; modern batches and client notifications fail closed;
• HTTP binding for MCP-Protocol-Version, Mcp-Method, and Mcp-Name;
• protocol-defined HeaderMismatch and unsupported-version errors;
• resultType: "complete" and cache metadata;
• initialize-era compatibility for 2025-11-25 and 2024-11-05.

The authority manifest is advertised through MCP discovery under the experimental mission-authority/v1 capability.

Security boundary

The adapter does not claim:

• that a model or chat UI authenticated the principal;
• that a review receipt is an approval grant;
• exactly-once behavior at an external provider;
• independent conformance or production validation;
• global trust in an agent.

Use @trust-graduation/core to create and validate exact grants. The executor must authenticate the grant issuer, re-bind the actual provider input, atomically consume the key, invoke the provider at most once, and reconcile unknown provider outcomes.

Open-core boundary

Free and open:

• this MCP adapter;
• @trust-graduation/core and its schemas;
• @gomission/mission-schemas conformance vocabulary;
• the A2A exact-action authorization extension;
• Mission Lite’s local focus app.

Commercial Mission may provide managed policy, trusted approval surfaces, hosted audit/receipt operations, organization controls, support, and provider integrations. Product entitlements never grant action authority.

Links

• Protocol: https://trustgraduation.org/
• A2A extension: https://trustgraduation.org/extensions/a2a/action-authorization/v1
• Mission: https://gomission.io/
• Source: https://github.com/gomission/mcp

License

Apache-2.0. Mission names and logos are trademarks; the code license does not grant permission to imply endorsement.