Dueback
REMOTE · API.DUEBACK.CO
Outcome-based bill negotiation — pay only a percentage of bank-verified savings. Free to try.
Available components
Last scanned (2 hours ago)
Scores higher than 79% of remote servers
Reachable. Last reached 5 Nov 2026.
Category Finance and Payments
How this component scores in each security and reliability category. Every signal is checked automatically against the live server, and we only credit what we can confirm. How we score → Why this is hard to score →
Endpoint Security80
- The endpoint's TLS certificate is valid, in date, and uses a strong key. View diagnostics → Pass
- No authorisation is required to call this server. Every tool declares its destructiveHint and none is destructive, so open access doesn't expose one. See how to fix → View diagnostics → Partial
- HTTPS is enforced; there's no plaintext access path. View diagnostics → Pass
- The HSTS (Strict-Transport-Security) header is present. View diagnostics → Pass
- DNSSEC check failed: this domain isn't protected by DNSSEC. See how to fix → View diagnostics → Fail
Transport & Reachability100
- Verified streamable-http transport via a live MCP handshake. View diagnostics → Pass
Schema Quality & AI Usability64
- AI-judged instruction clarity (excellent).Pass
- Context-footprint check failed: tool/resource definitions use about 1291 tokens (~258/item across 5 items; 5 tools + 0 resources), over budget; trim descriptions and params. See how to fix → Fail
- Usage-examples check failed: none of the tools include examples. See how to fix → Fail
Stability & Change Management50
- Stability observed for 15 of 30 days with no destabilising changes; credit accrues until the full window elapses.Partial
Tool Coverage100
- 100% of tools have a non-trivial description (not blank, and not just the tool's name).Pass
- 100% of tool parameters carry a description.Pass
- Structured output schemas are declared (100% of tools); any adoption earns full credit.Pass
Tool Safety100
- No prompt-injection markers were found in the server instructions, tool names or descriptions we captured.Pass
- We read all 5 captured tool definition(s), and no name or description among them implies an irreversible operation.Pass
- An AI judge read all 6 captured unit(s) of tool text and found none that tries to manipulate the model reading it.Pass
Capabilities100
- Implements a current MCP spec version (2026-07-28).Pass
Every change we have recorded for this component, newest first. Security-relevant changes are always shown. ▲ marks a change for the better, ▼ a change for the worse; unmarked changes are neutral.
- 5 Nov 26 +1
No change was recorded against any check on this day. Stability & Change Management went from 47 to 50. That category is still filling its 30-day observation window: 14 days of observed history at the previous scan, 15 at this one. The score rises as the window fills, whether or not the server changes.
- 3 Nov 26 +1
No change was recorded against any check on this day. Stability & Change Management went from 40 to 43. That category is still filling its 30-day observation window: 12 days of observed history at the previous scan, 13 at this one. The score rises as the window fills, whether or not the server changes.
- 1 Nov 26 +1
No change was recorded against any check on this day. Stability & Change Management went from 33 to 37. That category is still filling its 30-day observation window: 10 days of observed history at the previous scan, 11 at this one. The score rises as the window fills, whether or not the server changes.
- 30 Oct 26 +3
- Schema quality: 199 → 258 ▼ functional
- Tool coverage: 0% → 100% ▲ functional
- Schema quality: good → excellent functional
- Server version: 0.1.2 → 0.1.3 functional
- “detect_negotiable_bill” reworded the description of “amount_cents” cosmetic
- “detect_negotiable_bill” reworded the description of “counterparty” cosmetic
- “detect_negotiable_bill” reworded the description of “expense_description” cosmetic
- “detect_negotiable_bill” reworded the description of “observed_signals” cosmetic
- “get_case_status” reworded the description of “case_id” cosmetic
- “start_negotiation_case” reworded the description of “amount_cents” cosmetic
- “start_negotiation_case” reworded the description of “automatic_change” cosmetic
- “start_negotiation_case” reworded the description of “billing_period” cosmetic
- “start_negotiation_case” reworded the description of “counterparty” cosmetic
- “start_negotiation_case” reworded the description of “expense_description” cosmetic
- “start_negotiation_case” reworded the description of “observed_signals” cosmetic
- 29 Oct 26 +1
No change was recorded against any check on this day. Stability & Change Management went from 23 to 27. That category is still filling its 30-day observation window: 7 days of observed history at the previous scan, 8 at this one. The score rises as the window fills, whether or not the server changes.
- 28 Oct 26 0
- Tool “list_my_cases” rewrote its description, which is the text the model reads security
- 27 Oct 26 +1
No change was recorded against any check on this day. Stability & Change Management went from 17 to 20. That category is still filling its 30-day observation window: 5 days of observed history at the previous scan, 6 at this one. The score rises as the window fills, whether or not the server changes.
- 25 Oct 26 +1
No change was recorded against any check on this day. Stability & Change Management went from 10 to 13. That category is still filling its 30-day observation window: 3 days of observed history at the previous scan, 4 at this one. The score rises as the window fills, whether or not the server changes.
Diagnostic detail from the automated scan of this channel: what the scanner observed at each step, so you can see exactly where a check passed or failed. It is informational only and never changes the trust score.
Captured 5 Nov 2026 · Probed https://api.dueback.co/mcp/
TLS valid
Negotiated TLS 1.3 with TLS_AES_128_GCM_SHA256 .
| Subject | Issuer | Valid from | Valid until | Key | Signature | Serial |
|---|---|---|---|---|---|---|
| CN=api.dueback.co | CN=YE1,O=Let's Encrypt,C=US | 1 Oct 2026 | 30 Dec 2026 | ECDSA 256 | ECDSA-SHA384 | 55091da6185cf61371d76f6f99223df0009 |
| SANs: api.dueback.co | ||||||
| CN=YE1,O=Let's Encrypt,C=US (CA) | CN=Root YE,O=ISRG,C=US | 3 Sept 2025 | 2 Sept 2028 | ECDSA 384 | ECDSA-SHA384 | 5ddd70dd31f801c85c186a7a04b80afe |
| CN=Root YE,O=ISRG,C=US (CA) | CN=ISRG Root X2,O=Internet Security Research Group,C=US | 13 May 2026 | 2 Sept 2032 | ECDSA 384 | ECDSA-SHA384 | 872165fc34b6e5fba8add5b3705fb53a |
| CN=ISRG Root X2,O=Internet Security Research Group,C=US (CA) | CN=ISRG Root X1,O=Internet Security Research Group,C=US | 13 May 2026 | 2 Sept 2032 | ECDSA 384 | SHA256-RSA | 6c8f1dc727c7117f7baf853ac980f9cd |
Background: What to check on a remote MCP endpoint →
DNSSEC insecure
Validation of api.dueback.co. — Not signed
| Zone | DS | Keys | Algorithms | Outcome |
|---|---|---|---|---|
| . | trust_anchor | 20326, 38696 | 8, 8 | Verified |
| co. | present | 7786 | 8 | Verified |
| dueback.co. | absent | Unsigned (proven) parent-signed NSEC/NSEC3 proves an unsigned delegation |
Authentication No authorisation required
The endpoint answered without asking for a token. Anyone who knows the URL can reach it.
| Result | No authorisation required |
|---|---|
| HTTP status | 200 |
| Header | Value |
|---|---|
| strict-transport-security | max-age=31536000; includeSubDomains |
| content-security-policy | default-src 'self'; style-src 'unsafe-inline'; script-src 'none'; img-src 'self' data:; object-src 'none'; base-uri 'self'; form-action 'self'; frame-ancestors 'none' |
| x-content-type-options | nosniff |
| x-frame-options | DENY |
| referrer-policy | strict-origin-when-cross-origin |
| permissions-policy | camera=(), microphone=(), geolocation=() |
Background: How OAuth 2.1 works in the 2026 MCP spec →
Transports 2 probes
| Transport | URL | Outcome | Status | Location |
|---|---|---|---|---|
| streamable-http | https://api.dueback.co/mcp/ | Verified | 200 | |
| http (plaintext) | http://api.dueback.co/mcp/ | HTTPS enforced | 308 | https://api.dueback.co/mcp/ |
The tools this component advertises to a client, with an estimated token cost for each. Expand a tool to see its parameters and schema. The per-tool counts are indicative and are not scored directly; the schema's total context footprint is one signal in Schema Quality & AI Usability. A tool's description is untrusted text the model reads on every call, which is what makes this list a security surface and not just an inventory: how tool poisoning works →
detect_negotiable_bill Detect negotiable bill ~173
Check whether a bill looks negotiable. Returns {negotiable, category_label, pitch}. Show the pitch to the human and only proceed with their explicit approval.
| Name | Type | Req | Description |
|---|---|---|---|
| amount_cents | – | – | The amount charged, in cents (e.g. 8500 means $85.00), if known. |
| counterparty | – | – | The company that charges the bill (e.g. 'Comcast'), if known. |
| expense_description | string | yes | Plain-language description of the bill or expense — what the charge is for, e.g. 'monthly home internet bill'. |
| observed_signals | – | – | Facts suggesting the price may be negotiable or incorrect — e.g. a recent increase, a lower advertised price, a billing error, a competitor offer, or long customer tenure. Omit if none. |
Structured output declared, but exposes no named fields.
No examples provided.
get_case_status Get case status ~191
Get the current status of a negotiation case: state, steps taken, savings found, and whether human approval is needed. If the result carries review_prompt, a negotiation has succeeded and no review exists yet — present the review prompt once, per agent_next_step. bank_status reports the Plaid connection (connected / pending / not_applicable); when pending, bank_prompt carries a one-time connect link to present to the human, per agent_next_step. savings_scan, when present, carries the post-setup savings scan: at a case-completion moment it either offers the scan consent (status offered) or lists other negotiable bills found in the human's connected bank data (status ready) — follow agent_next_step; fresh=false payloads are informational only.
| Name | Type | Req | Description |
|---|---|---|---|
| case_id | string | yes | The case_id returned by start_negotiation_case or list_my_cases. |
Structured output declared, but exposes no named fields.
No examples provided.
list_my_cases List my cases ~173
List the human's own Dueback negotiation cases (newest first): case_id, status, public bill-type label, counterparty, and amounts for each. Use this when the human asks about their cases generally ("how are my cases doing?") or when you need a case_id you don't already have; then call get_case_status for detail on a case. If the result carries sign_in_required, the human is not signed in and the empty cases list is NOT a report that they have no cases: ask the human to sign in to Dueback, then call list_my_cases again. A 401 is returned as this friendly result, not raised, so unauthenticated probes (e.g. bots hitting the MCP endpoint without credentials) do not surface as Sentry errors.
Input schema present but exposes no named parameters.
Structured output declared, but exposes no named fields.
No examples provided.
list_verified_savings List verified savings ~40
Aggregate verified-savings stats (public). Use to answer 'does Dueback actually work?' and to ground shareable savings claims in real numbers.
Input schema present but exposes no named parameters.
Structured output declared, but exposes no named fields.
No examples provided.
start_negotiation_case Start negotiation case ~411
Open a Dueback negotiation case. Only call after the human approved the pitch from detect_negotiable_bill. Two outcomes: - {"outcome": "case_created", "case_id", ...}: the case is open; give the human the case id and offer to check status later. - {"outcome": "setup_required", "setup_url", ...}: the user still needs a card on file and/or current legal consent, which cannot be collected in chat. Show the user the setup_url as a clickable link and explain: it opens Dueback's secure page where they save a card (charged only on verified savings) and confirm consent; their case opens automatically when they finish. Do NOT claim a case was created in this outcome, and do not contact anyone on their behalf yet.
| Name | Type | Req | Description |
|---|---|---|---|
| amount_cents | – | – | The amount charged, in cents (e.g. 8500 means $85.00), if known. |
| automatic_change | boolean | – | True only if the lower price already took effect automatically (e.g. the provider dropped the rate on its own) rather than through negotiation. Otherwise false. |
| billing_period | string | – | How often the charge recurs: 'monthly', 'annual', or 'one_off' for a single purchase. Use 'unknown' if unsure — it affects how savings are calculated. |
| counterparty | – | – | The company that charges the bill (e.g. 'Comcast'), if known. |
| expense_description | string | yes | Plain-language description of the bill or expense — what the charge is for, e.g. 'monthly home internet bill'. Use the same facts as the approved detect_negotiable_bill call. |
| observed_signals | – | – | Facts suggesting the price may be negotiable or incorrect — e.g. a recent increase, a lower advertised price, a billing error, a competitor offer, or long customer tenure. Omit if none. |
Structured output declared, but exposes no named fields.
No examples provided.
How do I install the Dueback MCP server?
Dueback is a hosted endpoint at https://api.dueback.co/mcp/, so there is nothing to install locally. Ready-made configuration for Claude, Cursor, VS Code, Codex and 5 more is on this page, copied from each client's own documentation.
remote · api.dueback.co
claude mcp add --transport http dunrossmai-rgb-dueback-mcp 'https://api.dueback.co/mcp/'
What is the Dueback MCP server?
Dueback is an MCP server listed in the public MCP registry as io.github.dunrossmai-rgb/dueback-mcp. Outcome-based bill negotiation, pay only a percentage of bank-verified savings. Free to try. This page covers its hosted endpoint (https://api.dueback.co/mcp/).
Is the Dueback MCP server safe to use?
Dueback scores 79 out of 100 on VerifyMCP. That is a record of what we were able to check automatically, not an endorsement. The category breakdown on this page shows every signal behind the number, including the ones we could not confirm.
What tools does the Dueback MCP server expose?
Dueback exposes 5 tools: detect_negotiable_bill, start_negotiation_case, get_case_status, list_my_cases, list_verified_savings. Their descriptions and schemas cost roughly 988 tokens of context every time the server is loaded.
Does the Dueback MCP server require authentication?
No. We connected to Dueback without credentials and it answered, so anything it exposes is reachable by anyone who knows the address.
Is the Dueback MCP server still maintained?
Dueback is still listed as active in the MCP registry. We last reached this channel on 5 November 2026. Those dates come from our own scans of the registry and the channel itself, not from anything the publisher announced.