Crossmint API + Docs MCP by Crossmint

# Fix list: Crossmint API + Docs MCP

From Anchor Terminal's listing at https://www.anchorterminal.com/tools/crossmint, the October 2026 research run, assessed 1 October 2026. Grade B, 67.4 out of 100.

This is everything the published grade says the listing lacks, the biggest possible gain to the total first. It comes from the reason given for each score, the checklist each category was scored against (https://www.anchorterminal.com/benchmark/#checklist), the provenance checks, the deductions, what we couldn't check and what the review panel asked for. A fix counts at the next check, once it's public.

For a coding agent working on Crossmint API + Docs MCP: work through the items below in the product, its docs and its public pages. Each category gives the reason for its score, with the points each checklist item earned, and the checklist itself, so the gap is the items that earned less than their points. Change the product, not the wording, and keep a note of what you changed and where it's published.

## 1. Reliability, 53 out of 100, up to 9.4 more on the total

Why it scored 53: status.crossmint.com redirects to a Datadog-hosted status page (20). That page renders only in JavaScript and its /history and /api/v2/incidents.json paths redirect to the same page, so we couldn't read any incident history (5). Rate limits published, 120 writes and 360 reads a minute per project on self-serve plans, with higher limits for token and minting endpoints (15). The limits page says a 429 comes back and to wait briefly, with no Retry-After or backoff guidance, but transaction and transfer creation take an `x-idempotency-key` header and wallet creation returns the existing wallet for the same owner (8 of 15). Enterprise gets "premium SLAs" through sales, and no SLA is published (0). Wallets are generally available, but Agent Checkouts runs in production only with no staging, and the wallets spec still routes balances and transfer history through `/unstable` paths (5 of 10).

The checklist (https://www.anchorterminal.com/benchmark/#checklist-reliability):

Hosted APIs, MCP servers, models and platforms.

- 20, a public status page with component history (Statuspage, Instatus, BetterStack or the vendor's own).
- 0 to 30, the incident record for the last 90 days on that page. 30 for a clean record or trivial incidents only, 20 for minor incidents only, 10 for one major outage (an hour or more of a core API down, or errors across the board), 0 for several. 5 when there's no history we could read, and the note says so.
- 15, rate limits documented with numbers.
- 15, documented 429 or overload handling (Retry-After, backoff guidance), and idempotency keys or safe-retry guidance where writes are involved.
- 10, an SLA published for any paid tier.
- 10, the surface agents use is generally available, not beta or preview.

Local packages, SDKs, frameworks and stdio MCP servers.

- 20, installs from an official package with supported runtimes stated.
- 25, a public CI and test suite, passing on the default branch.
- 0 to 25, open crash or regression issues relative to activity (25 for few and handled, 0 for many, old and unanswered).
- 15, semver discipline and breaking changes called out in a changelog.
- 15, version 1.0 or later, or declared stable.

Protocols are read from their reference implementations, the public facilitators or servers, spec stability and test vectors.

## 2. Payments & pricing, 50 out of 100, up to 6.3 more on the total

Why it scored 50: Payment platforms and wallets take the highest step that applies on the 40-point protocol line. 40 for x402, MPP or L402 on all their own endpoints, 30 on part of their own API, 25 when their merchants can accept one, 20 for running a facilitator, 15 for paying as a buyer, 0 for only a protocol of their own. Crossmint's own API isn't paid over x402 or MPP. Crossmint's n8n node (n8n-nodes-crossmint 1.1.0, 12 November 2025) puts an x402 paywall in front of a workflow and settles to an address the seller sets through the Corbits facilitator, so the merchant step, though only for n8n (25 of 40). Agent Wallets also pay x402 and MPP endpoints for the buyer. Wallet overage at $0.02 per monthly active wallet and tokenisation at $0.01 an action are public, while onramp, offramp, checkout, orchestration, Agent Cards and Agent Checkouts have no published price (10). 1,000 free monthly active wallets with up to 2,000 transactions, and free staging on testnets, but the pricing page doesn't say whether a card is needed (15). A person signs up in the console to get keys (0).

The checklist (https://www.anchorterminal.com/benchmark/#checklist-payments):

The published rubric, also on the [x402 page](https://www.anchorterminal.com/x402/).

- 40, a machine payment protocol (x402, MPP or L402) on the tool's own endpoints. 10 to 30 when it covers only some endpoints or only goes through a third party, and the note says which.
- 20, per-call or per-unit pricing published without a login. 10 for public plan-only pricing, 0 for "contact sales" or prices behind a login.
- 20, a free tier or trial that doesn't need a card.
- 20, autonomous onboarding, meaning an agent can get access without a person signing up in a browser (keyless use, x402, a programmatic key API).

Payment platforms and agent wallets rarely charge for their own API over a machine protocol, so the first line has steps for them, and the highest one that applies counts. 40 when x402, MPP or L402 runs on all their own endpoints, 30 when it runs on part of their own API, 25 when their merchants can accept one, 20 for running a facilitator, 15 for paying as a buyer, and 0 when the only protocol is their own. Merchant acceptance sits above a facilitator because the platform's own customers can charge agents through it, while a facilitator settles for sellers who wire up the protocol themselves. The counter-argument (a facilitator does more for the protocol as a whole) has a point. Each note says which step applied.

Open-source software you run yourself is scored on its hosted or paid option if it has one. A free, self-hosted package with nothing to buy gets 20, 20 and 20 for the last three lines, and 0 to 40 for the first only if it ships a payment protocol.

## 3. Schema & documentation, 71 out of 100, up to 4.7 more on the total

Why it scored 71: A Crossmint Wallets API OpenAPI 3.0 file with 39 paths sits in the public SDK repo, but we found none for payments, onramp, Agent Cards or Agent Checkouts (15 of 25). llms.txt with about 450 entries, an llms-full.txt, and every page served as Markdown by appending `.md` (10). Operation descriptions state the purpose and the API scope each call needs, with little on when not to use them (12). Typed DTOs with required fields, though wallets are addressed by formatted locator strings such as `email:<email>:<chainType>` (11). Payment and onramp error-code pages, and the wallets spec documents 400, 404, 409 and 422 responses, with code samples in the quickstarts (11). Date-versioned paths (`/2025-06-09/`) and a docs changelog, but its newest entry is 11 February 2026, so recent API changes are only in the SDK changelogs (12).

The checklist (https://www.anchorterminal.com/benchmark/#checklist-schema):

APIs and MCP servers.

- 25, a machine-readable contract (a public OpenAPI file or similar; for MCP, typed JSON Schema inputs on every tool).
- 10, llms.txt or Markdown docs served for agents.
- 0 to 20, descriptions that say what a tool is for, when to use it and when not to, read from the tool definitions in the source or the API reference.
- 0 to 15, typed inputs with enums, constraints and required fields, and no free-form JSON blobs.
- 0 to 15, examples and documented error responses.
- 15, versioning and a public changelog.

Models are read from the API reference, the OpenAPI file, llms.txt, the structured-output and tool-use docs and the model cards. Frameworks from docs a model can follow, typed interfaces, examples and the API reference.

## 4. Agent ergonomics, 71 out of 100, up to 4.7 more on the total

Why it scored 71: No payments or wallet MCP server, only a one-tool docs search server. Responses can be narrowed by `chains` and `tokens` filters and `perPage` (15). Page and cursor pagination with date-range and status filters on transactions and transfers (18). Error-code pages for payments and typed SDK errors such as `RecoveryMethodRequiredError` and `InvalidChainError`, with less for the wallet REST errors (13). Idempotency keys on transaction and transfer creation, and wallet creation is idempotent per owner (17). Official SDKs are TypeScript only (browser, React, React Native and Node), with no second language found in the SDK repo (8).

The checklist (https://www.anchorterminal.com/benchmark/#checklist-ergonomics):

- 0 to 25, context cost. For MCP, the number and size of the tool definitions (25 for ten or fewer compact tools, 15 for 11 to 30, 5 for more than 30, plus up to 10 back for toolsets, dynamic loading or read-only subsets). For APIs, whether responses can be sized (field selection, limits, summaries).
- 20, pagination, filtering and output-size controls.
- 20, actionable, documented error responses, codes and messages an agent can recover from.
- 20, idempotency or safe retries, and for MCP the `readOnlyHint` and `destructiveHint` annotations.
- 15, sensible defaults, few required parameters, and official SDKs in at least two languages.

Models are read for tool use, structured output, prompt caching, context length, batch and SDKs. Frameworks for how much code and how many defaults a tool-calling agent with MCP needs.

## 5. Security & auth, 73 out of 100, up to 4.7 more on the total

Why it scored 73: Separate server-side and client-side API keys with named scopes such as `wallets:transactions.create`, and client keys can require a JWT from your own auth provider. Key rotation wasn't checked (25). Agent Wallets add the agent as a delegated signer with onchain spend caps, allowed counterparties and time windows, transactions carry an approvals step, and Agent Checkouts stops at a hard cap set per run (18). Agent Checkouts browses any merchant URL and we found no prompt-injection guidance for it (7). Transaction lists and webhooks give per-transaction visibility, and we found no API audit log (8). security.txt points to a disclosure policy with a 5 working day reply and 10 working day triage commitment, cash rewards only by exception, and a footer that cites SOC 2 and a Trust Centre. The same footer lists a Spanish CNMV crypto-asset service provider authorisation, FinCEN MSB registration and FINTRAC registration (15).

The checklist (https://www.anchorterminal.com/benchmark/#checklist-security):

- 0 to 30, the credential model. 30 for OAuth 2.1 with scopes, or scoped and revocable keys with rotation. 20 for plain revocable API keys. 10 for one all-powerful key. 10 off when a secret can travel in a URL query string as a documented option.
- 0 to 20, read-only or least-privilege modes, and confirmation or approval for destructive actions.
- 0 to 15, prompt-injection posture where the tool returns untrusted content (documented mitigations or guidance). A tool that returns no untrusted content gets 10.
- 0 to 15, audit logs or per-call visibility for the operator.
- 0 to 20, a security programme. security.txt or a disclosure policy, a bug bounty, SOC 2 or ISO 27001, advisories handled in public.

Models are read for retention, whether API data trains models (and whether that's off by default), zero-retention options and certifications. Frameworks for telemetry defaults, approval hooks, guardrails and sandboxing.

## 6. Transparency & trust, 83 out of 100, up to 1.5 more on the total

Made of editorial 65, provenance 100.

Why it scored 83: The SDKs are Apache-2.0 and the API is closed under published terms (18). Privacy policy updated 26 June 2026 names six Crossmint entities, states DPAs with each provider, keeps Persona biometric data no more than three years and otherwise retains data "as long as necessary", and uses SCCs and the EU-US Data Privacy Framework. It says personal data isn't used to train general-purpose models (20). The changelog dates deprecations, such as Checkout V2 ending on 30 October 2025, and SDK changesets give migration steps for removed chains (15). Subprocessors are listed on the Trust page, which we didn't open, and transfers outside the EEA are disclosed (12).

The checklist (https://www.anchorterminal.com/benchmark/#checklist-transparency):

- 0 to 30, source availability and licence clarity. 30 for open source under an OSI licence, 15 for closed with clear terms, 0 for unclear terms.
- 0 to 30, data handling and retention statements that agree with each other (privacy policy, DPA, retention periods, subprocessors).
- 0 to 20, a deprecation policy or notices with dates.
- 0 to 20, telemetry disclosed with an opt-out (local software), or subprocessors and data locations disclosed (hosted).

The other half of Transparency and trust is the provenance score, computed from checked facts (below). The category score is the mean of the two.

## 7. Maintenance & community, 85 out of 100, up to 1.3 more on the total

Why it scored 85: Release packages commit on 1 October 2026 shipped @crossmint/wallets-sdk 1.19.0 (30). 16 release commits since 1 July (20). Per-package changesets are detailed and current, but the docs changelog hasn't had an entry since 11 February 2026, and we didn't read the GitHub issue queue (12 of 25). Current official TypeScript SDKs (15). CI runs build and Vitest tests on every branch, plus smoke and end-to-end regression workflows. The 1.18.0 release removed deprecated chain names in a patch-level change that stops old code compiling, with migration notes (8).

The checklist (https://www.anchorterminal.com/benchmark/#checklist-maintenance):

- 0 to 30, time since the last release, or the last published model or API change for a closed service. 30 within 30 days, 20 within 90, 10 within 180, 0 older.
- 20, at least three releases or dated changelog entries in the last 90 days.
- 0 to 25, responsiveness. Issues and pull requests answered on GitHub (the open issues and how recent the replies are). For closed services, a public changelog and a support or community channel that answers, 0 to 15.
- 15, presence in the official MCP registry under a verified namespace (MCP servers), or current official SDKs (APIs and models).
- 10, package health, current dependencies and CI.

Models are read for deprecation notice periods and model churn rather than release counts.

## What we couldn't check

What we couldn't read counted as absent. Publishing it on a page a plain HTTP fetch can read (not only in a browser) lets the next check count it.

- unchecked: incident history for the last 90 days, because the Datadog status page renders only in JavaScript
- unchecked: whether the free tier needs a card
- unchecked: the subprocessor list on the Trust page and the SOC 2 report type
- Whether Agent Checkouts still sits under an `/api/unstable` path, as the 30 September check found

## Weaknesses

- No published price for onramp, offramp, checkout, Agent Cards or Agent Checkouts
- Agent Checkouts runs in production only, so the first test spends real money
- Status history is on a JavaScript-only Datadog page, and the docs changelog stops at 11 February 2026
- No MCP server for wallets or payments, only a one-tool docs search
- SDKs in TypeScript only

## What costs an agent a turn today

The notes we give agents before they call it. Each one is a workaround an agent shouldn't need.

- Send an `x-idempotency-key` on every transaction or transfer create so a retry can't pay twice
- Use staging keys against testnets; production keys work on mainnets only, and Agent Checkouts has no staging at all
- On 429, wait and retry. No Retry-After header is documented, and writes are capped at 120 a minute per project
- Use Agent Wallets for x402 and MPP endpoints and Agent Cards for card merchants; they aren't interchangeable
- Append `.md` to any docs URL for a Markdown copy

## What the review panel asked for

- Add a staging mode to Checkouts
- staging for Agent Checkouts
- checkout injection guidance

## When it's done

Send what changed and where it's published as a dispute (https://www.anchorterminal.com/builders/#disputes, or `POST https://www.anchorterminal.com/api/v1/contact` with `"kind": "dispute"`). Disputes are answered in public, and the listing is checked again by the same checklist. Paying for an audit or a listing claim changes nothing here.