Click on "Deploy Server".
Wait a few minutes for the server to deploy. Once ready, it will show a "Started" state.
In the chat, type @ followed by the MCP server name and your instructions, e.g., "@FabTally Utility Belt convert 5 miles to kilometers"
That's it! The server will respond to your query, and you can continue using it as needed.
Here is a step-by-step guide with screenshots.
The deterministic micro-utilities AI agents call constantly, as an MCP server (stdio + streamable-HTTP) and a pay-per-call HTTP API. One reliable bundle instead of thirteen flaky npm deps.
Free tools return real results with no wallet: convert, text, hash, encode, id, regex.
Paid tools ($0.001/call, x402 · USDC on Base): timezone, cron, rrule, currency, diff,
jsonschema, datemath. With no payment a paid tool returns the decoded x402 402 challenge
(price / network / asset / payTo) so an agent can pay and retry with x_payment. Humans can instead
prepay by card and use an X-FabTally-Key credit key against the HTTP API.
This server holds no private key. It fronts https://belt.fabtally.com. Every utility is a pure,
deterministic function with strict input validation; bad input → 400, never charged; nothing is stored.
Tool | Tier | What it does |
| free | Unit conversion (length/mass/temperature/volume/data/time/area/speed/angle/pressure/energy). |
| free | slugify · case-convert (camel/pascal/snake/kebab/constant/…) · |
| free | sha256/sha512/sha384/sha1/md5/sha3-256/keccak256/ripemd160, optional HMAC, hex/base64 out. |
| free | base64 / base64url / hex / url / html encode & decode. |
| free | uuid v4/v7, ULID, nanoid, random hex/base64url/int (count up to 1000). |
| free | test/match/extract/replace with catastrophic-backtracking protection (killable worker + timeout). |
| $0.001 | Instant → IANA zone with historically-correct DST; offsets, abbreviations, DST flags. |
| $0.001 | Cron expression → next N run times + plain-English description. |
| $0.001 | iCal RRULE (RFC 5545) → next N occurrences. |
| $0.001 | Live currency conversion at reference/mid-market rates (keyless ECB feed, cached). |
| $0.001 | Text diff: unified patch + structured op-list + add/remove/hunk stats. |
| $0.001 | Validate against JSON Schema (draft 2020-12) and explain every error in plain English. |
| $0.001 | Add/subtract ISO-8601 durations, diff into chosen units, business-day add/diff. |
Related MCP server: mcp-server-devutils
// claude_desktop_config.json
{
"mcpServers": {
"fabtally-belt": { "command": "npx", "args": ["-y", "fabtally-belt-mcp"] }
}
}Or clone and run: node index.js (speaks MCP over stdio).
Hosted: https://belt.fabtally.com/mcp. Or self-host: MCP_HTTP_PORT=8108 node http.js.
FABTALLY_BELT_BASE — API base (default https://belt.fabtally.com).
A paid tool with no x_payment returns:
{ "payment_required": true, "http_status": 402,
"challenge": { "x402Version": 2, "accepts": [ { "scheme": "exact", "network": "eip155:8453",
"amount": "1000", "asset": "0x833589fCD6eDb6E08f4c7C32D4f71b54bdA02913", "payTo": "0x…" } ] } }Build an x402 payment authorization (EIP-3009 transferWithAuthorization to payTo) for the accepts
entry and call the tool again with the token in x_payment. amount is atomic USDC (1000 = $0.001).
Deterministic. Stateless — no PII or request data stored. Receive-only wallet (no custody). Currency figures are reference/mid-market rates for informational use, not a dealable quote. MIT licensed.
FREE. Convert a value between units in the same dimension: length, mass, temperature, volume, data, time, area, speed, angle, pressure, energy. Deterministic. Args: value (number), from (unit), to (unit). e.g. {value:100, from:'c', to:'f'} or {value:1, from:'GiB', to:'MB'}. Different-dimension conversions 400.
Inputs: to (required), from (required), value (required).
PAID $0.001. Parse a 5- or 6-field cron expression and return the next N run times plus a plain-English description. Args: expression, timezone (IANA, default UTC), count (default 5), from (ISO, optional). Without payment returns the x402 challenge; pass x_payment to settle.
Inputs: expression (required), from, count, timezone, +1 more.
PAID $0.001. Convert an amount between currencies at reference/mid-market rates from a keyless public central-bank feed (ECB), cached. Informational, not a dealable quote. Args: amount, from, to (ISO-4217, e.g. USD, EUR, JPY). Without payment returns the x402 challenge; pass x_payment to settle.
Inputs: to (required), from (required), amount (required), x_payment.
PAID $0.001. Calendar date math. op='add'/'subtract' an ISO-8601 duration (P1Y2M10DT2H30M) to a date; op='diff' two datetimes into chosen units; op='business-add' add business days (configurable weekend + holidays); op='business-diff' count business days between two dates. Without payment returns the x402 challenge; pass x_payment to settle.
Inputs: op (required), to, date, days, +7 more.
PAID $0.001. Diff two texts: a unified patch, a structured op-list (add/remove/equal), and add/remove/hunk stats. Args: a, b, mode (lines|words|chars, default lines), context (default 3), label_a, label_b. Without payment returns the x402 challenge; pass x_payment to settle.
Inputs: a (required), b (required), mode, context, +3 more.
FREE. Encode or decode text. op is one of base64-encode|base64-decode|base64url-encode|base64url-decode|hex-encode|hex-decode|url-encode|url-decode|html-encode|html-decode. Args: op, text.
Inputs: op (required), text (required).
FREE. Compute a cryptographic digest: sha256, sha512, sha384, sha1, md5, sha3-256, keccak256, ripemd160. Optional HMAC via hmac_key. Output hex (default), base64, or base64url. keccak256 also returns a 0x-form (handy for Ethereum). Args: algorithm, text (+ input_encoding utf8|hex|base64, output_encoding, hmac_key).
Inputs: text (required), algorithm (required), hmac_key, input_encoding, +1 more.
FREE. Generate identifiers. kind is one of uuidv4|uuidv7|ulid|nanoid|hex|base64url|int. count up to 1000. nanoid takes size; hex/base64url take bytes. Uses a CSPRNG. Args: kind, count.
Inputs: kind, size, bytes, count.
PAID $0.001. Validate a value against a JSON Schema (draft 2020-12) and explain every error in plain English (which property, what was wrong, allowed values). Args: schema (object), data (any). Without payment returns the x402 challenge; pass x_payment to settle.
Inputs: schema (required), data, x_payment.
FREE. Run a regular expression against input with catastrophic-backtracking protection (it runs in a killable worker with a hard timeout, so a pathological pattern returns a 400 instead of hanging). op is test|match|extract|replace. Args: pattern, input, flags (gimsuy), op, replacement (for replace).
Inputs: input (required), pattern (required), op, flags, +2 more.
PAID $0.001. Expand an iCal RRULE (RFC 5545) recurrence into its next N occurrences. Args: rrule (e.g. 'FREQ=WEEKLY;BYDAY=MO,WE;COUNT=10'), after (ISO, default now), count (default 5), timezone. Tip: include DTSTART for anchored series. Without payment returns the x402 challenge; pass x_payment.
Inputs: rrule (required), after, count, timezone, +1 more.
FREE. Text transforms. op='slugify' -> URL slug; op is one of camel|pascal|snake|kebab|constant|dot|path|title|sentence|upper|lower for case conversion; op='template' fills {{placeholders}} from data. Args: op, text (for slugify/case), or template + data (for template).
Inputs: op (required), data, text, strict, +2 more.
PAID $0.001 (x402, USDC on Base). Convert an instant between IANA time zones with historically-correct DST. Returns converted datetime, UTC offsets, tz abbreviations, DST flags, and the offset difference. Args: datetime (ISO 8601 or epoch), from_zone, to_zone. Without payment returns the x402 challenge; pass x_payment to settle. Free teaser exists on the HTTP API at /v1/timezone/free.
Inputs: to_zone (required), datetime (required), from_zone, x_payment.
Recent tool additions, removals, and schema changes observed during successful MCP inspections.
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Scored across 13 tools
Each tool targets a unique function—encoding, unit conversion, text transforms, hashing, ID generation, regex, timezone, cron, RRULE, currency, diffing, JSON schema validation, and date math. Even the date-related tools (timezone, datetime, cron, rrule) are clearly differentiated by their descriptions.
All tool names are single lowercase words (encode, convert, text, hash, id, regex, timezone, cron, rrule, currency, diff, jsonschema, datemath), forming a consistent and predictable naming scheme. There is no mixing of styles or conventions.
With 13 tools, the server is well-scoped for a general-purpose utility belt. Each tool covers a distinct domain, and the count falls comfortably within the ideal 3-15 range.
The server covers a broad range of common utilities: encoding, conversion, text manipulation, crypto, IDs, regex, time/date, currency, diffing, and validation. Minor gaps exist, such as JSON formatting or URL parsing, but these are not critical for the stated purpose.
Remote MCP for JSON repair, hashing, formatting, IDs, dates, units, and other small tools.
Developer utilities MCP server: base64, hash, slug, uuid v4, timestamp, urlencode. Free, no key.
Read-only developer, date, finance, and text utilities. Authless remote MCP server by Clean.tools.
Tiny devtools MCP server: slugs, timestamps, case conversion, hashing, base64, UUIDs.
