Approval MCP Server

A multi-stage approval workflow engine for ADK-Rust Enterprise legal and media-content agents. 17 MCP tools: configurable workflow templates, stage rules (all-of / any-of / quorum), decisions with delegation and escalation, SLA/expiry clocks, and an immutable audit trail on every action.

Yes — this is the approval-workflow server

An approval system is a workflow engine. One model — an ApprovalRequest moving through an ordered set of Stages, each with a decision rule and eligible approvers — serves every agent below. The variety is in the routing, not the mechanics.

| Domain | Agent | Typical workflow shape | |--------|-------|------------------------| | Legal | Board Consent Drafter | single stage, quorum (N-of-M directors) | | Legal | Contract Review Agent | sequential Legal → Finance → Exec | | Legal | Policy Compliance Reviewer | compliance sign-off gate | | Media | Brand Compliance Reviewer | brand any-of review | | Media | Content Localization Agent | linguistic QA → in-country review | | Media | Publishing QA Agent | editorial QA gate | | Media | Rights Clearance Assistant | rights review → legal clearance | | Media | Social Post Producer | fast content review before publish |

Architecture

Core Concepts

• Workflow template — a reusable, ordered list of stages for a request type. Eight defaults ship (one per agent above); create your own with create_workflow.
• Stage rule — how a stage resolves from its votes:
  • all_of — every eligible approver must approve
  • any_of — one approval advances
  • quorum — at least N approvals (e.g. 3 of 5 directors)
• Decision — approve · reject · request_changes · abstain. A reject fails the request; request-changes bounces it back to the requester for resubmission.
• Delegation — an approver can delegate authority; the delegate's vote is recorded on behalf of the original (preserved in the audit trail).
• Escalation — reassign the active stage to new approvers (e.g. on SLA breach).
• Audit trail — every mutation appends an immutable entry (actor, action, timestamp). Essential for board consents and legal sign-offs.

Tools (17)

Agentic (2)

| Tool | What It Does | |------|-------------| | intake_and_route | Create and submit a request in one step, auto-selecting the default workflow for the type | | request_status | Concise status: workflow position, approvals vs. needed, outstanding approvers, next step |

Workflow Templates (3)

| Tool | What It Does | |------|-------------| | list_workflows | List templates (optionally by domain) | | get_workflow | Get a template's full stage definitions | | create_workflow | Define a custom workflow (stages, rules, approvers, SLAs) |

Requests & Lifecycle (6)

| Tool | What It Does | |------|-------------| | create_request | Open a request bound to a workflow (optionally submit) | | get_request | Full detail: stages, votes, comments, attachments, audit | | search_requests | Filter by text, domain, type, status, approver | | submit_request | Route a draft for review (activate first stage) | | cancel_request | Withdraw a request (gated) | | escalate | Reassign the active stage to new approvers (gated) |

Decisions & Collaboration (6)

| Tool | What It Does | |------|-------------| | decide | Record a decision on the active stage; evaluates the rule (gated) | | my_queue | Requests awaiting a given approver | | delegate | Delegate approval authority for a request (gated) | | add_comment | Comment on the request thread | | add_attachment | Attach a document/evidence reference (by URI) | | get_audit_trail | Immutable record of who did what, when |

Example — board written consent (quorum 3 of 5)

> intake_and_route(domain: "legal", request_type: "board_consent",
    title: "Approve 2026 budget", requester: "secretary", subject_ref: "consent:BUDGET-2026")
  → routed AR-1003 · active stage "Board Vote" (quorum)

> decide(id: "AR-1003", approver: "dir.1", decision: "approve")   → in_review (1 of 3)
> decide(id: "AR-1003", approver: "dir.2", decision: "approve")   → in_review (2 of 3)
> decide(id: "AR-1003", approver: "dir.3", decision: "approve")   → approved  (quorum met)

> get_audit_trail(id: "AR-1003")
  → created · submitted · decision ×3 · stage_approved · approved

Example — contract review (sequential, with delegation)

> create_request(request_type: "contract_review", title: "MSA with Acme",
    requester: "legalops", subject_ref: "contract:MSA-ACME", submit: true)
  → AR-1010 · stage "Legal Review"

> delegate(id: "AR-1010", from: "legal.counsel", to: "legal.associate", reason: "OOO")
> decide(id: "AR-1010", approver: "legal.associate", decision: "approve")
  → advances to "Finance Review"  (vote recorded on behalf of legal.counsel)

Installation

1. Build

git clone https://github.com/zavora-ai/mcp-approval
cd mcp-approval
cargo build --release

2. Add to your MCP client

Claude Desktop / Kiro / Cursor / Windsurf:

{
  "mcpServers": {
    "approval": {
      "command": "/path/to/mcp-approval"
    }
  }
}

3. Use it

> list_workflows(domain: "media_content")
> intake_and_route(domain: "media_content", request_type: "social_post",
    title: "Launch thread", requester: "social.producer", subject_ref: "post:LAUNCH-01")

Governance & Data Handling

• Gated writes — decide, cancel_request, escalate, and delegate require approval in production (requires_approval); reads are read_only.
• Defensible audit — every state change is recorded immutably with actor and timestamp.
• No raw documents — items under approval and attachments are opaque references/URIs, never embedded content.
• Integration scaffold — the in-memory store is for development; back it with a durable store and bind approver/actor to authenticated identities in production.

MCP Server Manifest

server_id = "mcp_approval"
display_name = "Approval Workflows"
version = "1.0.0"
domain = "governance"
risk_level = "high"
writes_allowed = "gated"
transports = ["stdio"]

Contributors

|
_{James Karanja Maina} | |:---:|

License

Apache-2.0 — see LICENSE for details.

Part of the ADK-Rust Enterprise MCP server ecosystem.

Registry Compliance

This server implements the ADK MCP SDK contract:

• HealthCheck — async health probe for registry monitoring
• mcp-server.toml — manifest declaring tools, risk classes, and approval gates
• Structured tracing — RUST_LOG env-filter for observability