Swell by Swell

# Fix list: Swell

From Anchor Terminal's listing at https://www.anchorterminal.com/tools/swell, the October 2026 research run, assessed 1 October 2026. Grade C, 55.1 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 Swell: 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. Security & auth, 35 out of 100, up to 11.4 more on the total

Why it scored 35: One secret key per environment (test or live) with full access to every collection, revocable, plus public keys for the Frontend API (15). No scoped or read-only secret key found. Role-based permissions are listed only on the Unlimited plan (5). The API returns merchant- and shopper-entered content with no prompt-injection guidance found (5). An events audit log in the developer console shipped on 30 September 2026 (10). No security.txt (the path redirects to itself per the 30 September check), no disclosure policy or bug bounty found, and no SOC 2 or PCI claim on the pages we read (0).

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.

## 2. Payments & pricing, 25 out of 100, up to 9.4 more on the total

Why it scored 25: No x402, MPP or L402 (0). Plan prices are public with per-unit overage, $5 per extra 100K API requests and $5 per extra GB, plus 2 to 0.4 per cent above each sales ceiling (15). No free plan. A free trial on every plan, with the card requirement not stated (10). A person signs up in the browser (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. Reliability, 63 out of 100, up to 7.4 more on the total

Why it scored 63: Atlassian Statuspage at status.swell.store with Backend API, Frontend API, Dashboard, Hosted Checkout, CDN and Storefronts, and a history link (20). We could read only the last 15 days, which show a scheduled database maintenance on 30 September (11:00 to 13:00 PDT, service possibly unavailable) and nothing else. The incident feed was refused by our fetch rate limit, so the rest of the 90 days is unchecked. A clean partial window earns half (15). Throughput and concurrency limits are per store and environment, with the weighting formula documented but the numbers unpublished. Monthly quotas of 100K, 500K and 2M requests are public (5). Requests over the limit queue, a 429 means one waited more than 60 seconds, and transactions return typed 408, 409 and 429 codes. No Retry-After or idempotency keys found (8). "100% uptime SLA" listed for the Unlimited plan, with no SLA terms published (5). Generally available (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.

## 4. Agent ergonomics, 65 out of 100, up to 5.7 more on the total

Why it scored 65: `limit` (Frontend API maximum raised to 1,000 in December 2025) and `expand` and `include` controls, with heavier expands costing rate-limit weight. Field selection not confirmed (15). Page envelopes with `count`, `page` and `page_count`, plus `where` operators, sort and search (20). Validation errors carry a code per field, but invalid writes return HTTP 200 with an `errors` object, so an agent that doesn't check them reports success (15). No idempotency keys. Transactions roll back only on request errors, and there's no undo for merges (5). Official JavaScript libraries only (swell-node and swell-js), with simple Basic auth (10).

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. Schema & documentation, 68 out of 100, up to 5.2 more on the total

Why it scored 68: No OpenAPI file. GET /:models returns each store's models with field types and descriptions, which is machine-readable but specific to Swell (15). developers.swell.is/llms.txt returns 404, but Swell's MIT-licensed Claude Code skills carry about 320 KB of Markdown reference for agents (7). The skills say which API fits which job and list the non-obvious rules, such as PUT deep-merging arrays by element id (15). Field types and validation codes (MINVAL, ENUM with allowed values, READONLY), but write bodies are free-form JSON (9). Status codes and validation objects documented with examples (13). Monthly dated changelog with no API versioning (9).

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.

## 6. Transparency & trust, 51 out of 100, up to 4.3 more on the total

Made of editorial 31, provenance 71.

Why it scored 51: Closed platform with published terms, and MIT SDKs and skills (15). Privacy policy updated 19 August 2026 names Stripe, Google Analytics and Leadfeeder, but gives no retention periods, no DPA and no postal address (10). No deprecation policy or dated notices found (0). Transfers to the US stated, with no hosting provider or subprocessor list (6).

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.

Provenance checks not met in full (half of this category, computed from checked facts):

- Domain age: swell.is, registered 2019-09-06 (7 years) (11 of 15)
- Endpoint on the vendor's domain: api.swell.store is not on swell.is (0 of 15)
- security.txt: not found (0 of 10)

## 7. Maintenance & community, 82 out of 100, up to 1.6 more on the total

Why it scored 82: Changelog entry on 30 September 2026 and swell-js 5.9.1 on 29 September (30). Monthly changelog entries on 31 July, 31 August and 30 September, and swell-js 5.8.1, 5.8.2, 5.9.0 and 5.9.1 since 30 July (20). Monthly changelog and email and chat support on every plan (12). swell-js is current, swell-node's last tag is 6.0.5 from 18 May 2026, and the official skills plugin was updated on 25 September. No Swell MCP server in the registry (12). Test workflows in both SDK repos (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 before 17 September 2026 (the history feed was refused by our fetch rate limit)
- Whether the free trial needs a card
- Where the "Security and Privacy page" linked from the privacy policy lives. Two likely URLs returned 404
- Whether the API supports field selection to trim responses

## Weaknesses

- One full-access secret key per environment, with no scoped or read-only key
- Invalid writes return HTTP 200 with an errors object
- Rate-limit numbers aren't published
- No llms.txt, OpenAPI, security.txt or disclosure policy
- No DPA, subprocessor list or deprecation policy found

## 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.

- Call GET /:models once and cache it. It's the ground truth for custom fields
- Check `result.errors` after every write. A failed validation still returns 200
- Use `$set` to replace an array. A plain PUT merges arrays by element id and never shrinks them
- Use an sk_test_ key while testing. A bare sk_ prefix is live
- Keep `expand` and `include` small. Each level past the first three points adds rate-limit weight

## What the review panel asked for

- Non-200 on validation failure
- Official MCP server
- scoped secret keys
- a disclosure policy

## 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.