Spec Driven Development
MCP Server that facilitates spec-driven development workflows, not just Vibe Coding.
Description from the maker (original English)
RevRec schedules, renewals, credits, usage pricing. Can save contracts and renewals as drafts.
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This address needs a key in a request header, which the add-connector menu cannot set. Use Claude Code, Cursor or VS Code instead.
Run this in your terminal
claude mcp add --transport http defrr https://defrr.com/v1/mcp --header 'Authorization: your-value'Fill in the empty values before running it.
Paste into .cursor/mcp.json in your project, or ~/.cursor/mcp.json
{
"mcpServers": {
"defrr": {
"url": "https://defrr.com/v1/mcp",
"headers": {
"Authorization": "your-value"
}
}
}
}Your browser asks to open the app, then the app shows the settings and asks you to confirm. Key values are left empty for you to fill in.
Paste into .vscode/mcp.json in your project
{
"servers": {
"defrr": {
"type": "http",
"url": "https://defrr.com/v1/mcp",
"headers": {
"Authorization": "your-value"
}
}
}
}Your browser asks to open the app, then the app shows the settings and asks you to confirm. Key values are left empty for you to fill in.
This address needs a key in a request header, which the add-connector menu cannot set. Use Claude Code, Cursor or VS Code instead.
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Authorization secret required HTTP headerThese settings are generated from the maker’s registry entry. If the README says otherwise, follow the README.
We have not read this server’s tool list yet; we check endpoints in rotation.
We check information anyone can see; we have not read the code. Checks that do not apply are left out of the count. · Checked Nov 6, 2026
The registry name was verified against the domain defrr.com (the registry checks domain ownership)
We have not read this repo from GitHub yet
We have not read this repo from GitHub yet
Not checked yet; we check endpoints in rotation
Not checked yet; we check endpoints in rotation
Not checked yet; we read the tool list when we check the endpoint
Compared with every active server in this category in the registry. Stars count only when the publisher owns the repo.
It passed 1 of 1 applicable basic checks. We have not read the code. Before adding a key or token, see what access the server asks for and use a key with only the permissions you need.
You need to fill in: Authorization
It runs in the maker’s cloud. Connect over the internet with nothing to install, but what you send passes through the maker’s servers.
The GitHub repo last changed –, and the latest version (1.3.0) reached the registry 10 days ago.
Apps that support MCP, such as Claude Desktop, Claude Code, Cursor and VS Code. It connects by URL, so apps that accept remote MCP servers work too, such as ChatGPT in developer mode.
In the same category: Spec Driven Development, Remote Desktop Commander, LickityClick
Servers in the same category from other makers, sorted by stars.
Reading a card:★ GitHub starsiThree pillars: reviews · checks · usageiUpdated = latest version published to the registryi
MCP Server that facilitates spec-driven development workflows, not just Vibe Coding.
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Create, edit and track LickityClick short links, campaigns and click stats from your AI assistant.
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Revenue recognition (RevRec) schedules, waterfalls, renewals, credits, cancellations and usage pricing for contracts, worked out by defrr's engine. Connect it to Claude Code and ask in plain English, or call it from your own code.
The calculation tools store nothing, and nothing you send to them is logged. If you want, you can also switch on saving to your defrr organization (see below): contracts and renewals are saved as drafts a person approves, and usage products can be set up. That is off by default and set per key.
claude mcp add --transport http defrr https://defrr.com/v1/mcp \
--header "Authorization: Bearer dfr_live_YOUR_KEY"
/mcp. defrr should show 9 tools for a key that only calculates, or 18 or 23 for a key that can also save contracts (see below).These calculate and store nothing. They work for every key.
| Tool | What it does | Credits |
|---|---|---|
defrr_create_contract | New contract: terms in, month-by-month schedule out. Saves nothing | 1 |
defrr_create_waterfall | Up to 50 contracts at once: each contract's billing, revenue and deferred balance by month, and the total | 1 per contract |
defrr_process_renewal | Renewals: the price change, the billing entry, the revised schedule, and what to post by month. A renewal processed after it started has its catch-up posted in the first open month | 1 per renewal |
defrr_usage_billing | What usage costs under flat, volume, prepaid-credit or fixed-fee-plus-overage pricing, month by month. Prepaid overage is flagged; a fixed fee's overage is priced and returned apart from revenue. Give a fixed-fee line a startDate and dated usage and its cycles follow the contract's anniversary: the fee is booked in the month each cycle starts and the overage in the month it ends. Stateless: your usage is calculated and returned, never stored | 1 per line |
defrr_reprice_renewal | Credit for a renewal priced too high | 2 |
defrr_reprice_contract | Credit for an original term priced too high | 2 |
defrr_cancel_renewal | Cancel the latest renewal | 2 |
defrr_cancel_contract | Cancel a whole contract | 2 |
defrr_get_credit_balance | Check your credits | Free |
A call that fails is refunded.
By default the tools above only calculate: the schedule comes back to you and nothing is kept. If you want contracts and renewals recorded in your defrr organization, create a key with Save contracts in Defrr ticked on your developer account. If you don't have a defrr workspace yet, the page sets up a small one for you (company name, base currency, how revenue is recognised and, if you like, the month your books are locked through). A key without that option can only calculate.
| Tool | What it does | Needs | Credits |
|---|---|---|---|
defrr_save_contract | Saves a contract as a draft and works out its schedule | the save option | 1 (a repeat is free) |
defrr_list_drafts | Lists the drafts waiting for approval, or already decided | the save option | Free |
defrr_get_workspace | Shows the organization, its base currency and recognition model, its locked period, how many drafts are waiting, and when the key last connected | the save option | Free |
defrr_approve_draft | Makes a draft a live contract | the approve option | Free |
defrr_reject_draft | Discards a draft (it is kept as rejected) | the approve option | Free |
defrr_save_renewal | Saves a renewal for a contract already in the workspace as a draft: the contract is not changed until the renewal is approved. Works for contracts whose terms can be read as a schedule, and refuses a renewal that starts in a closed period | a save or approve key | 1 (a repeat is free) |
defrr_list_renewal_drafts | Lists renewal drafts waiting for approval, or already decided | a save or approve key | Free |
defrr_approve_renewal_draft | Adds a draft renewal to its contract as a new last term and recalculates its schedules | the approve option | Free |
defrr_reject_renewal_draft | Discards a draft renewal (it is kept as rejected) | the approve option | Free |
defrr_find_contracts | Finds a customer's contracts in the workspace by name | a save or approve key | Free |
defrr_get_contract | Reads one contract and returns its terms as a schedule the calculation tools take. Says what is in the way when a contract has features the calculators don't model | a save or approve key | Free |
defrr_list_usage_products | Lists the usage products already set up in the workspace | a save or approve key | Free |
defrr_preview_usage_product | Shows what sample customers would pay under a usage product (pay as you go, prepaid credits or fixed fee plus overage) before it exists. Saves nothing | a save or approve key | Free |
defrr_create_usage_product | Creates that usage product in the workspace (a new product only; existing ones are edited in defrr) | the approve option | Free |
A saved contract is a draft. It isn't live, and no report reads it, until it is approved: in defrr under Contracts, Draft contracts, or by an agent whose key also has the approve option. Leave the approve option off for an agent you want a person to check. If a draft has revenue in months you have closed (your locked period in Organization details), or in months that have already ended, defrr says so before it is approved.
Repeats are safe. Sending the same agreement again returns the draft already saved and costs nothing, while that draft is waiting or approved. If it was rejected, or its contract has since been deleted, the same terms save as a new draft. Send an idempotencyKey to save a separate deal with identical terms.
A saved renewal is a draft too. When a customer renews, the agent finds the contract (defrr_find_contracts, then defrr_get_contract) and saves the renewal with defrr_save_renewal: the contract's id, the renewal's end date and the renewal term's total price. The contract does not change until the renewal is approved in defrr under Contracts, Draft renewals, or with defrr_approve_renewal_draft if the key may approve. Approving adds the renewal as a new last term and recalculates the contract's schedules. It only works on a contract whose terms can be read as a schedule (defrr_get_contract says why when it can't, for example monthly billing, a discount or a foreign currency), only after the contract's last end date, and it refuses a renewal that starts in a closed period: process that one in the app under Edit renewals.
What the agent is told. When a session starts it learns which organization it is connected to, the last locked period, and when the key last connected. Only a person can change the locked period, in defrr under Organization details.
In Claude Code, start a new session and type:
/mcp__defrr__new-contract
It asks for anything missing (customer, product, each term's dates and price, how revenue is recognised), reads the terms back for you to confirm, then saves a draft. You can put what you already know after the command. Other MCP clients list the same prompt as new-contract on the defrr server, in their own menu. Or just ask in plain English: "Create a contract for Acme Pty Ltd, Pro Plan, 1 Jan 2027 to 31 Dec 2027 at $12,000".
A workspace set up from the developer account page opens a few pages in the defrr app: the Dashboard, View all contracts, Draft contracts, Draft renewals, Usage products, the customer profile, and Organization details (the basic details, recognition model, base currency and locked period). The rest are subscription features and are shown greyed out.
It also has an Ask defrr assistant, a button at the bottom right of every page. It uses these same tools and your credits, and can also prepare the cancellation of a contract, or of its latest renewal: it shows the figures on a card and nothing changes until you press Confirm. It cannot approve drafts.
A new contract (calculate only):
Use defrr to create a contract: original term 1 Jan 2026 to 31 Dec 2026 at $12,000,
then a renewal from 1 Jan 2027 to 31 Dec 2027 at $18,000. End dates are included.
Recognise it smooth. Show me the terms and the month-by-month schedule.
A renewal:
Use defrr to process a renewal, recognised smooth with end dates included. The contract ran
1 Jan 2026 to 31 Dec 2026 at $12,000 and renews to 31 Dec 2027 at $18,000. Our books are
closed through March 2027. Show the price change, the billing entry, any catch-up, and what
to post by month.
Usage:
Use defrr to price usage for two customers. Acme is on volume pricing: the first 100,000 units
a month at $0.002, then $0.001 a unit above that. They used 250,000 units in Jan 2026 and
80,000 in Feb 2026. Globex has prepaid credit: 100,000 units at $0.002 each. They used 70,000
units in Jan 2026 and 60,000 in Feb 2026. Show each month's revenue, the total by month, and
any overage.
Saving a renewal (needs a key with the save option):
Acme Pty Ltd renewed their Pro Plan to 31 Dec 2028 for $14,000. Find their contract and save the
renewal as a draft. Tell me which contract you used.
Saving a contract (needs a key with the save option):
Create a contract in defrr for Acme Pty Ltd, Pro Plan: 1 Jan 2027 to 31 Dec 2027 at $12,000,
exact recognition, end date included. Tell me which organization it was saved to.
Any MCP client that supports Streamable HTTP and custom headers can connect. Send your key either as Authorization: Bearer dfr_live_YOUR_KEY or as X-API-Key: dfr_live_YOUR_KEY (for tools that don't let you set Authorization). Never put a key in the web address.
This repository is laid out as a Cursor plugin: the defrr connection (mcp.json, and the same file as .mcp.json for directories that look for that name), a rule that tells the agent when to use defrr (rules/defrr-revops.mdc), and a new-contract command that steps you through saving a contract (commands/new-contract.md).
The connection reads your key from an environment variable called DEFRR_API_KEY, so the key never goes into a file. Create a key at https://defrr.com/developers/account, then set the variable once:
launchctl setenv DEFRR_API_KEY dfr_live_YOUR_KEY
Then quit Cursor completely (Cmd+Q) and open it again from the Dock or Applications folder, not by typing a command in Terminal. Cursor reads the variable when it starts, so reloading the window is not enough. The setting lasts until you restart your Mac: run the command again after a restart, or use the file-based setup below.
DEFRR_API_KEY, then quit and reopen Cursor.Then check Cursor's MCP settings: defrr should be ready and list its tools (9 for a key that only calculates, 18 or 23 for a key that can save contracts).
To use the plugin before it is in Cursor's marketplace, copy this folder to ~/.cursor/plugins/local/defrr/ and reload Cursor.
If you would rather keep the key in a file, or Cursor can't see the variable, it shows defrr as failed, often with Unexpected token '<', "<!DOCTYPE"... is not valid JSON in its MCP log. That message means the request reached defrr without a valid key. Add the server yourself in ~/.cursor/mcp.json (or Cursor Settings, MCP):
{
"mcpServers": { "defrr": { "type": "http", "url": "https://defrr.com/v1/mcp", "headers": { "X-API-Key": "dfr_live_YOUR_KEY" } } } }
Keep this file out of version control, and if you use the plugin as well, t
Only the beginning is shown; read the rest in the repo