Fidacy action firewall for AI agents. Mandate-gated payment authorization as an MCP server.
Nothing to run from here
NullClear Arbiter is installed from its publisher's own source and answers where it runs, so this marketplace is not in the path of a single call. There is no address here to send one to, and a panel that pretended otherwise would be showing you an answer we made up. Install it and call it from your own client — the Installation tab has the entry for each one.
96/100
trust score
18
downloads a day
local
or remote
1k
downloads in 30d
What it does
Autonomous x402 payment schema-escrow arbiter, spend firewall, failover & ERC-8004 Sybil oracle
Quickstart
# 1 — add it to Claude Code
claude mcp add --scope user nullclear-arbiter-mcp '--' npx -y @nullclear/mcp
# 2 — ask your agent for something these tools do
# nullclear_check_reputation, nullclear_escrow_x402_call, nullclear_verify_kya_mandate and 10 more
NullClear Arbiter costs nothing on mcprush: there is no plan to choose here, no cap to set and nothing mcprush can bill you for.
Publisher
Installation
Where are you running it?
Every route below installs the same thing and ends at the same approval screen. This one can run either way — at an address its publisher runs, or as a process under your own user, with your files and your network — and this marketplace is in the path of neither.
Claude Codedeclared by this listing
This is a public server: you run it yourself and this marketplace is not in the path. You need Node.js — the current LTS (24) is the safe choice; npx comes with it. Claude Code registers it in one command; --scope user makes it available in every project. The '--' is in quotes so that PowerShell passes it on.
claude mcp add --scope user nullclear-arbiter-mcp '--' npx -y @nullclear/mcpReconnect, or start a new session, and the tools appear in the model’s tool list.
Or connect to its publisher’s address
Its publisher also runs it at https://api.nullclear.dev/mcp: nothing to start on your machine, and this marketplace is not in the path.
claude mcp add --scope user --transport http nullclear-arbiter-mcp https://api.nullclear.dev/mcpFree on mcprush, and it runs from its publisher’s own package: this marketplace is not in the path, so there is no key of ours to hold and no card to add.
What it writes
One config entry your client uses to start the process locally. A local server runs with your file system and your network, which is why it is priced without metering.
What you approve
13 tools, with what each one reads, writes and reaches shown before you agree — the same list on every route above. Read the tool surface.
Tool surface
What the model actually sees. Descriptions are diffed on every release — see version history.
Read from its source code. A server that builds its tool list when it starts can list more tools than this.
Inspect an AI agent's trust score (0-100), clearing reliability, Sybil wash-trade penalty flags, and corporate KYA backing on Base
| Parameter | Type | Required | Notes |
|---|---|---|---|
| agentId | string | yes | The ERC-8004 agent token ID or registered identifier |
| chainId | number | no | Base chain ID (8453 for Mainnet, 84532 for Sepolia) |
Execute an x402-gated HTTP API call through NullClear deferred schema escrow. The arbiter guarantees payment is only settled if upstream returns valid data matching your schema contract. If the seller hallucinates or crashes, $0 is spent.
| Parameter | Type | Required | Notes |
|---|---|---|---|
| targetUrl | string | yes | Upstream API endpoint demanding x402 payment |
| method | string | no | — |
| sellerAgentId | string | no | Seller's agent ID for reputation check and Sybil wash-trade gating |
| minTrustScore | number | no | Minimum acceptable trust score for seller (0-100, default 50) |
| requiredFields | array | no | Field paths that must exist in response |
| jsonSchema | object | no | JSON Schema draft-07 contract that response must strictly satisfy |
| invariants | array | no | Deep value invariants (numeric bounds, regex, forbidden substrings, timestamp freshness) |
| rejectRefusals | boolean | no | Reject canonical LLM refusal strings (default: true) |
| fallbacks | array | no | Ordered fallback candidates for autonomous multi-seller failover routing (max 3) |
| spendPolicy | object | no | Outbound spend firewall limits (maxPerCallAtomic, maxDailyWalletAtomic) |
Verify an agent's Know Your Agent (KYA) corporate liability mandate, active validity, and whether a proposed transaction amount is within corporate limits
| Parameter | Type | Required | Notes |
|---|---|---|---|
| agentId | string | yes | The ERC-8004 agent token ID |
| chainId | number | no | Base chain ID (default 8453) |
| transactionAmountUsd | number | yes | Amount in USD intended to spend in the transaction |
No parameter schema on file.
No parameter schema on file.
No parameter schema on file.
No parameter schema on file.
No parameter schema on file.
No parameter schema on file.
No parameter schema on file.
No parameter schema on file.
No parameter schema on file.
No parameter schema on file.
Free
$0 forever
- Every tool, no call limit
- No card, and mcprush charges nothing for it
- Source published under MIT
- Runs on your machine — nothing of it reaches our gateway
- Nothing to cap, because mcprush bills nothing
What counts against your monthly calls
| Tool | Unit | Calls used | Out of the allowance |
|---|
Nothing here is billable: mcprush charges nothing to install NullClear Arbiter or to call it, at any volume.
Call allowance · this installenforced at the gateway
Monthly allowance, in calls
—
—
Alert at 80% · then the tool returns a normal MCP error
Used this month: —
ATrust score 96 / 100
Release 1.3.2 · scanned 28 Oct 2026
Two independent axes, because powerful and malicious are different questions. The grade is threat only. The capability level is blast radius, and it is never a penalty on the grade — it is priced as one subtract-only term in the score, where you can see it.
Threat score100
Client score96
Findings0 threat · 3 capability
Capabilitymoderate
Coveragesource
Verificationrepo
Surface digest61d0e6ae4aca7373998a9601d4db0500bf198fa0b1a93e9feaf5a52d645d0a1b
Score vectorthreat 100 → client 96
| Term | Level | What it prices | Points |
|---|---|---|---|
| capability-exposure | moderate | capability blast radius (moderate) — client exposure if the model is manipulated | −3 |
| verification-discount | repo | publisher verification (public source) — no provenance, but the source is public and inspectable | −1 |
| coverage-honesty | source | inspection depth (source) — how much of the target the scan could see | −0 |
score = clamp(round(threatScore − E_cap − E_ver − E_cov), 0, 100). No model, no opinion, no network call at scoring time: the same methodology version against the same bytes always produces this number, and every line above is a field of the report rather than a summary of it.
What the scan could actually read
A grade is only as meaningful as its coverage, so the scanner publishes its own depth before it publishes its result.
Tool surfaceread
Implementation sourceread
Package metadataread
Live transportnot available
Tools were statically extracted from the published source (13 recovered), not enumerated from a running server. Tool-poisoning, Unicode-smuggling, capability and toxic-flow analysis ran on this inferred surface, but a mis-parsed registration could be missed or mis-attributed, so tool-derived findings are capped below “confirmed”. To grade the real runtime surface, scan the running server: --command "npx -y <package>".
Capability — what it could do if the model were manipulated
Tags derived from each tool’s schema and the implementation, not from what the tool calls itself. moderate is the level these add up to.
| Tool | Capability tags | Why the tag was assigned |
|---|---|---|
| scan_token_forensics | untrusted-input | untrusted-input: declares openWorldHint: true (interacts with entities outside the server) |
| inspect_contract_abi_and_proxy | untrusted-input | untrusted-input: declares openWorldHint: true (interacts with entities outside the server) |
| decode_calldata_or_failed_tx | untrusted-input | untrusted-input: declares openWorldHint: true (interacts with entities outside the server) |
| simulate_transaction_preflight | untrusted-input | untrusted-input: declares openWorldHint: true (interacts with entities outside the server) |
| read_url_clean_markdown | untrusted-input | untrusted-input: declares openWorldHint: true (interacts with entities outside the server) |
| nullclear_discover_verified_x402_apis | untrusted-input | untrusted-input: declares openWorldHint: true (interacts with entities outside the server) |
| nullclear_token_security_audit | untrusted-input | untrusted-input: declares openWorldHint: true (interacts with entities outside the server) |
| nullclear_wallet_risk_score | untrusted-input | untrusted-input: declares openWorldHint: true (interacts with entities outside the server) |
| nullclear_crypto_market_oracle | untrusted-input | untrusted-input: keyword "fetch", declares openWorldHint: true (interacts with entities outside the server) |
| nullclear_safe_fetch | untrusted-input | untrusted-input: keyword "fetch", declares openWorldHint: true (interacts with entities outside the server) |
| nullclear_escrow_x402_call | external-sink | external-sink: declares readOnlyHint: false, openWorldHint: true |
| nullclear_check_reputation | untrusted-input | untrusted-input: declares openWorldHint: true (interacts with entities outside the server) |
| nullclear_verify_kya_mandate | untrusted-input | untrusted-input: declares openWorldHint: true (interacts with entities outside the server) |
Toxic-flow graph
The lethal trifecta, checked as a graph rather than as a checklist: untrusted input, a sensitive source and an external sink have to meet before there is a path worth worrying about.
flow-1
Untrusted input can drive an external action even though no sensitive source is exposed.
Supply chain and provenance
Integrityfirst-seen
Surface digest61d0e6ae4aca7373
Scanned2026-10-28
This is the first scan of this surface here, so there is nothing yet to compare it against.
Every result on this tab comes from one deterministic pass over the published package — offline, rule by rule, and auditable line by line above. Same methodology version, same bytes, same score.
Release history
Always latest — the install command names no version, so it installs the newest release when it runs; the current release on file is 1.3.2. Pin a release below and the command asks for exactly that one.
1.3.2
28 Oct 2026
latestNo release note was published with this version.
1.2.0
17 Oct 2026
No release note was published with this version.
1.1.2
16 Oct 2026
No release note was published with this version.
1.1.1
undated
- The version this listing was on when mcprush began following its releases. The registry was not asked when it shipped, so this row carries no date.
—
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One review per account, from a signed-in account that does not publish this listing. Nothing else is asked — you can say what you think before you install it. Publishers can reply once per review, and a review can be edited or deleted by whoever wrote it.
Sign in to write one
Any signed-in account that does not publish NullClear Arbiter can review it, once — before installing it or after. A review from an account that has installed it is marked as one.
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Nobody has reviewed this listing. The rating on the card is the mean of the reviews written here and nothing else, so there is no rating until somebody writes the first — which takes a signed-in account that does not publish it, and nothing else.