Penny Engine — Agent Operations

by kasheik3 · remote · no sign-in to list tools · v0.7.7 · published by GitHub user kasheik3

Remote MCP utilities for agents: structured data, commerce checks, and x402 paid API discovery.

Deletes · 1Changes · 12

Compare Registry entry

18 tools: 1 can delete or cancel things, 12 change things and 5 only read.

Scanned Oct 21, 2026

Deletes or cancels1Claude Code: deny: see these tools
Can't be undone0Claude Code: ask
Changes things12Claude Code: ask: see these tools
Only reads5Claude Code: allow: see these tools

3 checks matched something in the tool definitions. No finding is not a safety guarantee. How the checks work.

claude mcp add --transport http penny-engine https://penny-agent-api-production.up.railway.app/mcp

Findings

Matches of fixed checks, with the text they matched.

3 warn

Warnpenny_url_clean
The server marks "penny_url_clean" read-only (readOnlyHint: true), and its own name, description or input give the class "destructive".
Matched text
annotations: {"readOnlyHint":true,"destructiveHint":false,"openWorldHint":false}; The description's first verb is "remove": a word for removing or ending something.
What this check looks for
Warnpenny_url_clean
The server marks "penny_url_clean" not destructive (destructiveHint: false), and its own name, description or input give the class "destructive".
Matched text
annotations: {"readOnlyHint":true,"destructiveHint":false,"openWorldHint":false}; The description's first verb is "remove": a word for removing or ending something.
What this check looks for
Warnpenny_catalog_import_guard
The server marks "penny_catalog_import_guard" read-only (readOnlyHint: true), and its own name, description or input give the class "write".
Matched text
annotations: {"readOnlyHint":true,"destructiveHint":false,"openWorldHint":false}; The name "penny_catalog_import_guard" says "import": a word for a change.
What this check looks for

Tools

Open a tool for its reasons and full description. Descriptions are the publisher's own words, shown as they are.

18 tools

Deletes or cancels 1Removes, cancels or revokes something.Claude Code: deny

penny_url_cleanRemove common tracking parameters from HTTP links without fetching.2 findings
Why it is in this group
- The description's first verb is "remove": a word for removing or ending something.
- The server marks it read-only (readOnlyHint: true), but an annotation never lowers a class.
- The server marks it not destructive (destructiveHint: false), but an annotation never lowers a class.
Findings
- Warn
  The server marks "penny_url_clean" read-only (readOnlyHint: true), and its own name, description or input give the class "destructive".
  Matched text
  annotations: {"readOnlyHint":true,"destructiveHint":false,"openWorldHint":false}; The description's first verb is "remove": a word for removing or ending something.
  What this check looks for
- Warn
  The server marks "penny_url_clean" not destructive (destructiveHint: false), and its own name, description or input give the class "destructive".
  Matched text
  annotations: {"readOnlyHint":true,"destructiveHint":false,"openWorldHint":false}; The description's first verb is "remove": a word for removing or ending something.
  What this check looks for
Description, as the server wrote it
Remove common tracking parameters from HTTP links without fetching. Free, no signup, deterministic.
Annotations the server declares
- readOnlyHint: true
- destructiveHint: false
- openWorldHint: false

Changes things 12Creates or changes something that can be changed back.Claude Code: ask

penny_campaign_economicsCustomer acquisition cost and break-even click price.No findings
Why it is in this group
- Nothing in its name or description says what it does, so it is counted as a write.
- The server marks it read-only (readOnlyHint: true), but an annotation never lowers a class.
Description, as the server wrote it
Customer acquisition cost and break-even click price. Free, no signup, deterministic.
Annotations the server declares
- readOnlyHint: true
- destructiveHint: false
- openWorldHint: false
penny_catalog_auditBatch-audit up to 50 product records for duplicate SKUs, missing attributes, malformed URLs and estimated net contribution per order.No findings
Why it is in this group
- Nothing in its name or description says what it does, so it is counted as a write.
- The server marks it read-only (readOnlyHint: true), but an annotation never lowers a class.
Description, as the server wrote it
Batch-audit up to 50 product records for duplicate SKUs, missing attributes, malformed URLs and estimated net contribution per order. Useful for scheduled ecommerce catalog ingestion and agent product publishing. No external network calls. Free, no signup.
Annotations the server declares
- readOnlyHint: true
- destructiveHint: false
- openWorldHint: false
penny_catalog_import_guardBefore importing a product scrape, compare current and previous batches.Reads text others write1 finding
Why it is in this group
- The name "penny_catalog_import_guard" says "import": a word for a change.
- The server marks it read-only (readOnlyHint: true), but an annotation never lowers a class.
What it can reach
- untrusted-inputThe description's first sentence says "scrape": it reads web pages, which anyone can write.
Findings
- Warn
  The server marks "penny_catalog_import_guard" read-only (readOnlyHint: true), and its own name, description or input give the class "write".
  Matched text
  annotations: {"readOnlyHint":true,"destructiveHint":false,"openWorldHint":false}; The name "penny_catalog_import_guard" says "import": a word for a change.
  What this check looks for
Description, as the server wrote it
Before importing a product scrape, compare current and previous batches. Flag duplicate IDs, missing records, invalid prices, currency changes, price jumps and stock anomalies. Return row-level allow/review decisions with before/after evidence. Free trial: 50 rows per snapshot, 16,000-character request. No fetching, storage, payment or automatic writes.
Annotations the server declares
- readOnlyHint: true
- destructiveHint: false
- openWorldHint: false
penny_choose_serviceGiven an agent's real task, get the single best supported Penny Engine payable route, exact $0.001 quote, required input, sample, and buyer-authorized checkout instructions.No findings
Why it is in this group
- Nothing in its name or description says what it does, so it is counted as a write.
- The server marks it read-only (readOnlyHint: true), but an annotation never lowers a class.
Description, as the server wrote it
Given an agent's real task, get the single best supported Penny Engine payable route, exact $0.001 quote, required input, sample, and buyer-authorized checkout instructions. Includes optional FREE CSV preflight; does not sign, pay or execute a paid call.
Annotations the server declares
- readOnlyHint: true
- destructiveHint: false
- openWorldHint: false
penny_cleaning_quoteCommercial cleaning quote by labor and target margin.No findings
Why it is in this group
- Nothing in its name or description says what it does, so it is counted as a write.
- The server marks it read-only (readOnlyHint: true), but an annotation never lowers a class.
Description, as the server wrote it
Commercial cleaning quote by labor and target margin. Free, no signup, deterministic.
Annotations the server declares
- readOnlyHint: true
- destructiveHint: false
- openWorldHint: false
penny_csv_to_jsonTransform CSV text into a bounded array of JSON records with quoted cell support.No findings
Why it is in this group
- Nothing in its name or description says what it does, so it is counted as a write.
- The server marks it read-only (readOnlyHint: true), but an annotation never lowers a class.
Description, as the server wrote it
Transform CSV text into a bounded array of JSON records with quoted cell support. Free, no signup, deterministic.
Annotations the server declares
- readOnlyHint: true
- destructiveHint: false
- openWorldHint: false
penny_fulfillment_preflightFREE preflight for a catalog audit or agent-output-batch-qa work order, with $0.001 Base USDC checkout instructions.No findings
Why it is in this group
- Nothing in its name or description says what it does, so it is counted as a write.
- The server marks it read-only (readOnlyHint: true), but an annotation never lowers a class.
Description, as the server wrote it
FREE preflight for a catalog audit or agent-output-batch-qa work order, with $0.001 Base USDC checkout instructions. Never charges, signs, or executes the paid call.
Annotations the server declares
- readOnlyHint: true
- destructiveHint: false
- openWorldHint: false
penny_html_extractExtract structured page title, meta tags, headings and JSON-LD from supplied HTML without browsing or executing scripts.No findings
Why it is in this group
- Nothing in its name or description says what it does, so it is counted as a write.
- The server marks it read-only (readOnlyHint: true), but an annotation never lowers a class.
Description, as the server wrote it
Extract structured page title, meta tags, headings and JSON-LD from supplied HTML without browsing or executing scripts. Free, no signup, deterministic.
Annotations the server declares
- readOnlyHint: true
- destructiveHint: false
- openWorldHint: false
penny_marginUnit margin, markup and break-even units.No findings
Why it is in this group
- Nothing in its name or description says what it does, so it is counted as a write.
- The server marks it read-only (readOnlyHint: true), but an annotation never lowers a class.
Description, as the server wrote it
Unit margin, markup and break-even units. Free, no signup, deterministic.
Annotations the server declares
- readOnlyHint: true
- destructiveHint: false
- openWorldHint: false
penny_marketplace_profitEcommerce net contribution after goods, fees, ads and shipping.No findings
Why it is in this group
- Nothing in its name or description says what it does, so it is counted as a write.
- The server marks it read-only (readOnlyHint: true), but an annotation never lowers a class.
Description, as the server wrote it
Ecommerce net contribution after goods, fees, ads and shipping. Free, no signup, deterministic.
Annotations the server declares
- readOnlyHint: true
- destructiveHint: false
- openWorldHint: false
penny_slugifyTurn a short string into a lowercase ASCII URL slug.No findings
Why it is in this group
- Nothing in its name or description says what it does, so it is counted as a write.
- The server marks it read-only (readOnlyHint: true), but an annotation never lowers a class.
Description, as the server wrote it
Turn a short string into a lowercase ASCII URL slug. Free, no signup, deterministic.
Annotations the server declares
- readOnlyHint: true
- destructiveHint: false
- openWorldHint: false
penny_subscription_ltvSimple monthly churn lifetime value estimates.No findings
Why it is in this group
- Nothing in its name or description says what it does, so it is counted as a write.
- The server marks it read-only (readOnlyHint: true), but an annotation never lowers a class.
Description, as the server wrote it
Simple monthly churn lifetime value estimates. Free, no signup, deterministic.
Annotations the server declares
- readOnlyHint: true
- destructiveHint: false
- openWorldHint: false

Only reads 5Looks things up and changes nothing.Claude Code: allow, ask for 1 outbound

penny_capability_routerResolve an agent task to existing Penny Engine capabilities only.No findings
Why it is in this group
- The description's first verb is "resolve": a word for reading.
Description, as the server wrote it
Resolve an agent task to existing Penny Engine capabilities only. Does not execute, purchase, research live web content, or claim to handle arbitrary tasks. Unsupported requests are labeled explicitly. Free, no signup.
Annotations the server declares
- readOnlyHint: true
- destructiveHint: false
- openWorldHint: false
penny_json_inspectParse and inspect bounded JSON input without retaining it.No findings
Why it is in this group
- The name "penny_json_inspect" says "inspect": a word for reading.
Description, as the server wrote it
Parse and inspect bounded JSON input without retaining it. Free, no signup, deterministic.
Annotations the server declares
- readOnlyHint: true
- destructiveHint: false
- openWorldHint: false
penny_product_evidenceRetrieve current public product metadata and variant details from supported Allbirds and tentree product URLs.Reads text others writeCan send data outNo findings
Why it is in this group
- The description's first verb is "retrieve": a word for reading.
What it can reach
- untrusted-inputThe server marks it openWorldHint: true: it reaches things outside the server's own data.
- untrusted-inputThe input takes a URL (input.url), and the tool reads it: it reads web pages, which anyone can write.
- outboundThe input takes a URL (input.url): a request to a URL can carry data to whoever runs it.
Claude Code: ask, because it is tagged outbound.
Description, as the server wrote it
Retrieve current public product metadata and variant details from supported Allbirds and tentree product URLs. Return source timestamps, hashes, field provenance, conflicts and changes versus a caller-supplied previous snapshot. Narrow free preview; no browser rendering, purchases or background monitoring.
Annotations the server declares
- readOnlyHint: true
- destructiveHint: false
- openWorldHint: true
penny_target_priceFind minimum price for target gross margin after fees.No findings
Why it is in this group
- The description's first verb is "find": a word for reading.
Description, as the server wrote it
Find minimum price for target gross margin after fees. Free, no signup, deterministic.
Annotations the server declares
- readOnlyHint: true
- destructiveHint: false
- openWorldHint: false
penny_trend_radarGet recent US Google Trends rising-search queries and transparent heuristic purchase-intent classification to identify digital product research candidates.Reads text others writeNo findings
Why it is in this group
- The description's first verb is "get": a word for reading.
What it can reach
- untrusted-inputThe server marks it openWorldHint: true: it reaches things outside the server's own data.
Description, as the server wrote it
Get recent US Google Trends rising-search queries and transparent heuristic purchase-intent classification to identify digital product research candidates. Public RSS, cached 10 minutes, no customer or sales data. Free, no signup.
Annotations the server declares
- readOnlyHint: true
- destructiveHint: false
- openWorldHint: true

This is not a safety rating, and no finding is not a safety guarantee. The groups and findings come from fixed checks of the tool definitions the server returned on the date shown, not from its code or what it does when called. How the checks work.

Exfil surface

Which tools read private data, which read text someone else can write, and which can send data out. One of each is a path a prompt injection can use.

No private-data, untrusted-input, outbound path in this server alone: no tool is tagged private-data.

Reads private data0: Reads files, mail, messages, databases, secrets, calendars or repositories.
Reads text others write3: Brings in text someone else can write: web pages, inbound email, messages, issues and comments.; penny_catalog_import_guard
penny_product_evidence
penny_trend_radar
Can send data out1: Can carry data to people or systems: it sends, posts or publishes, or takes a recipient, channel or URL.; penny_product_evidence

Other servers in the same agent add their own tools to these paths. Audit your whole setup to see them together.

Remote posture

What anyone on the internet sees at the remote endpoint: an anonymous initialize and tools/list, and the public OAuth metadata.

Looked at Oct 22, 2026, 15:01 UTC, unchanged since Oct 22, 2026. No credentials were sent and no tool was called. What is looked at.

Reachable: yes
HTTP status of an anonymous initialize: 200
tools/list served without credentials: yes
Tools that change things, listed without credentials: 13
Protocol version: 2025-03-26
WWW-Authenticate on 401: not observed
resource_metadata in WWW-Authenticate: none
RFC 9728 protected resource metadata: none
Authorization servers: none
Legacy HTTP+SSE transport: no
Dynamic client registration: not observed
Client ID metadata documents: not observed

HighThe whole server
The endpoint served tools/list without credentials, and the list has 13 tools that change things (1 destructive, 12 write). Whether a call also works without credentials was not tested: tools are never called.
Matched text
https://penny-agent-api-production.up.railway.app/mcp: tools/list returned 18 tools to an anonymous client, including penny_url_clean (destructive), penny_margin (write), penny_cleaning_quote (write), penny_marketplace_profit (write), penny_campaign_economics (write) and 8 more
What this check looks for

Install

Pinned to version 0.7.7. Values in angle brackets are yours to fill in.

claude mcp add --transport http penny-engine https://penny-agent-api-production.up.railway.app/mcp

Run in a terminal.

Claude Code permissions

Allow the reads, ask before a change or a way out, deny the deletes. Paste into .claude/settings.json.

.claude/settings.json

{
  "permissions": {
    "allow": [
      "mcp__penny-engine__penny_target_price",
      "mcp__penny-engine__penny_json_inspect",
      "mcp__penny-engine__penny_trend_radar",
      "mcp__penny-engine__penny_capability_router"
    ],
    "ask": [
      "mcp__penny-engine__penny_margin",
      "mcp__penny-engine__penny_cleaning_quote",
      "mcp__penny-engine__penny_marketplace_profit",
      "mcp__penny-engine__penny_campaign_economics",
      "mcp__penny-engine__penny_subscription_ltv",
      "mcp__penny-engine__penny_slugify",
      "mcp__penny-engine__penny_html_extract",
      "mcp__penny-engine__penny_csv_to_json",
      "mcp__penny-engine__penny_catalog_audit",
      "mcp__penny-engine__penny_fulfillment_preflight",
      "mcp__penny-engine__penny_choose_service",
      "mcp__penny-engine__penny_catalog_import_guard",
      "mcp__penny-engine__penny_product_evidence"
    ],
    "deny": [
      "mcp__penny-engine__penny_url_clean"
    ]
  }
}

Tools that only read are allowed, tools that change things ask first, tools that delete or cancel are denied. A read that can send data out (it takes a URL, say) asks first too. It assumes the server is installed as penny-engine. Review it before you use it.

Capability tags behind 3 rules

mcp__penny-engine__penny_trend_radar untrusted-input
mcp__penny-engine__penny_catalog_import_guard untrusted-input
mcp__penny-engine__penny_product_evidence untrusted-input, outbound

Keep track

Get told when this server's tools change: a new tool, a new description, a new class.

https://anlyon.dev/servers/io.github.kasheik3/penny-engine/changes.xml

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Anlyon alternative

13 of these tools change something. Run those as governed actions.

Declare what an action changes, and Anlyon puts it under a shared limit, binds every approval to the exact request, and grades the outcome. It works on any HTTPS API you can describe as an action.

Anlyon does not run, proxy or govern this MCP server. A tool your own code calls directly is not routed through Anlyon and is not governed by it.

Import an OpenAPI spec →

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Source: MCP Registry. Synced Oct 21, 2026, 18:37 UTC.

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