Sprites

# Fix list: Sprites

From Anchor Terminal's listing at https://www.anchorterminal.com/tools/sprites, the October 2026 research run, assessed 8 October 2026. Grade C, 58.3 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 Sprites: 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, 55 out of 100, up to 9 more on the total

Why it scored 55: Hosted lines. status.flyio.net runs on incident.io with history and a Sprites component (20). Four Sprites incidents in the last 90 days. Deletion jobs failed for 47 minutes on 30 August 2026, a partial API outage ran 1 hour 38 minutes on 2 September, a partial outage ran 7 hours 28 minutes from 23 September, and creates failed in all regions outside Europe for 28 minutes on 8 October (5). The product page gives creation limits of 10 a minute on pay-as-you-go and 60 to 240 on plans, and 100 running Sprites on the Hero plan. No general request limits were found in the docs (10). The Go SDK reads `Retry-After` and `X-RateLimit` headers on a 429 and names a `sprite_creation_rate_limited` code, but the docs and the OpenAPI document list no 429 response and no idempotency keys (7). A 99.9 per cent uptime SLA is listed with Enterprise support, from $2,500 a month, without saying whether it covers Sprites (5). No beta label was found on Sprites, though the API document is version 0.1.12 and the SDKs are 0.x (8).

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, 30 out of 100, up to 8.8 more on the total

Why it scored 30: No x402, MPP or L402 (0). Unit prices are public without a login, $0.0385 a CPU-hour, $0.021875 a GB-hour of memory, $0.000683 a GB-hour of hot storage and $0.000027 a GB-hour of cold storage (20). New organisations get a $30 trial credit. Whether a card is needed to receive it was not established, so half credit (10). A person signs up with a Fly.io account in a browser and creates the token (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. Security & auth, 59 out of 100, up to 7.2 more on the total

Why it scored 59: Bearer tokens are created and removed at sprites.dev/account per organisation, with no scopes found. The MCP connector uses OAuth, and its default token can only create a capped number of Sprites under a name prefix (22). Sprite URLs are private by default, Connectors deny by default and can limit provider paths, and a privileges policy can drop capabilities. The network allowlist is opt-in, so egress is open by default (15). Connectors keep provider credentials out of the Sprite and the MCP page describes what its tools can destroy. No prompt-injection guidance was found (9). No audit log of API calls was found in the reviewed documentation (0). SOC 2 Type 2, named third-party penetration testers, published remediation times and security@fly.io. fly.io has no security.txt and no bug bounty was found (13).

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.

## 4. Agent ergonomics, 68 out of 100, up to 5.2 more on the total

Why it scored 68: List calls take `max_results`, and service logs take `lines` and `duration`. Exec returns command output directly, with a WebSocket route for streaming (17). Sprite lists page with `continuation_token` and filter by `prefix` (16). Status codes are listed per operation and the SDKs raise typed errors with a machine code, but no code list is published (10). No idempotency keys. Service creation is a PUT by name and Sprite names are unique per organisation, and the hosted MCP server marks tools as read-only or destructive (10). Creating a Sprite needs only a name, and there are official SDKs in four languages and a CLI (15).

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, 74 out of 100, up to 4.2 more on the total

Why it scored 74: A public OpenAPI 3.1 document with 44 operations and 59 schemas, plus an AsyncAPI file for the WebSocket calls (25). llms.txt and a Markdown copy of every docs page (10). Concept pages say when to use Services, Tasks and checkpoints and when not to, while operation descriptions are one line each (15). Request bodies have required fields and examples, but the document has 6 enums and no schema for error bodies (10). 116 examples in the OpenAPI document. Error responses are a status code and a short phrase, and the product page's create and exec examples disagree with the OpenAPI document (8). Paths are versioned under `/v1`. No API changelog was found, and only the Python SDK keeps a changelog file (6).

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, 59 out of 100, up to 3.6 more on the total

Made of editorial 54, provenance 64.

Why it scored 59: The SDKs are MIT and the platform is closed under terms of service effective 29 April 2026 (18). The privacy statement, effective 24 September 2026, keeps account data while the account is active and analytics data for at most 12 months. A pre-signed DPA is available on request. The terms grant Fly.io a licence to use customer data to run and improve the services. No retention period for Sprite data after deletion was found beyond the docs calling destruction permanent (18). No deprecation policy was found. The maintenance page says Sprites on Ubuntu 25.04 must upgrade, without a date (3). A sub-processor list of 34 vendors with countries and a dated change log, last updated 24 September 2026, names Tigris for Sprites object storage. The docs do not say which region a Sprite runs in (15).

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):

- Endpoint on the vendor's domain:  is not on fly.io (0 of 15)
- Terms of service: read, states 6 of the 7 things a reader expects (9.1 of 10)
- Changelog: not found (0 of 10)
- security.txt: not found (0 of 10)

## 7. Maintenance & community, 80 out of 100, up to 1.8 more on the total

Why it scored 80: `sprites-py` 0.7.2 on 6 October 2026, 2 days ago, and `@fly/sprites` 0.2.3 on 17 September (30). Six `sprites-py` releases and five `@fly/sprites` releases since 22 July 2026 (20). No product changelog was found. Support is the community forum below the Hero plan and email above it. Issue response on GitHub was not read (7). Current official SDKs for JavaScript, Go, Python and Elixir (15). All four SDK repositories run a checks workflow in CI. The JavaScript SDK requires Node.js 24 or later (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.

## Deductions

Each comes off the total. A fixed and documented problem counts for less at the next check.

- 2026-10-08: the Fly.io pricing page says of Sprites "No plans and no tiers", while the Sprites product page read the same day describes paid plans (Hero at $100 a month, Mythic at $2,000) that carry usage allowances and set concurrency and creation-rate limits. Prices for the other named plans were not found. 2 points. https://fly.io/pricing/ and https://fly.io/sprites/

## 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.

- The lead listed a CLI and SDKs for JavaScript, Go and Elixir. It left out the REST API at api.sprites.dev, the Python SDK (`sprites-py`) and the hosted MCP server at sprites.dev/mcp. The listing grades the REST API.
- Which create and exec shape the API accepts. The product page uses `PUT /v1/sprites/{name}` and a JSON `command` body, and the OpenAPI document uses `POST /v1/sprites` and `cmd` query parameters. We made no API calls.
- Whether the $30 trial credit needs a card. The product page says start free, and the general Fly.io trial page describes Machines only.
- Prices and allowances for the Adventurer, Veteran, Champion, Legend and Epic plans. Only Hero ($100) and Mythic ($2,000) are priced on the product page, and the pricing page says there are no plans.
- Whether the Enterprise 99.9 per cent uptime SLA covers Sprites.
- Whether Sprites run on Firecracker. Fly.io's security docs say compute jobs use Firecracker, and the Sprites docs say only hardware-isolated microVM.
- Which regions Sprites run in and whether a region can be chosen. Not found in the reviewed documentation.
- unchecked: GitHub stars, open issues and issue response times for the SDK repositories. The GitHub API refused our requests for a rate limit.
- unchecked: whether tokens created at sprites.dev/account can be scoped or given an expiry, and whether the dashboard has an audit log. Both need a login.
- unchecked: the number and definitions of the MCP server's tools, which need an OAuth sign-in to list.
- unchecked: the DPA text. The compliance page says it is pre-signed and available, and no public copy was found.
- No changelog for the API or the Sprite environment was found, so `provenance.changelog` is left empty.
- fly.io/llms.txt asks AI agents to send an `AI-Agent` request header, and the product page tells AI agents to refetch it as Markdown. Both are recorded as facts. We did not act on them.

## Weaknesses

- Four Sprites incidents on the status page in 90 days, including a partial outage of 7 hours 28 minutes on 23 September 2026 and failed creates outside Europe for 28 minutes on 8 October
- Outbound network access is unrestricted by default. The DNS allowlist is opt-in and set from outside the Sprite
- The product page creates a Sprite with `PUT /v1/sprites/my-sprite` and a JSON `command` body, while the OpenAPI document creates with `POST /v1/sprites` and passes `cmd` as a query parameter
- No API changelog, deprecation policy or error-code reference was found in the reviewed documentation
- The pricing page says Sprites have no plans and no tiers, while the product page describes paid plans that set concurrency and creation-rate limits
- No scopes were found for API tokens created at sprites.dev/account. Only the MCP connector's OAuth token is restricted by default

## 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.

- Create a token at sprites.dev/account after a browser signup, and send it as `Authorization: Bearer <token>` to `https://api.sprites.dev`
- Follow the OpenAPI document, not the product page example. Create with `POST /v1/sprites` and a JSON `name`, and run commands with `POST /v1/sprites/{name}/exec` using `cmd` query parameters
- Set a network policy with `POST /v1/sprites/{name}/policy/network` before running untrusted code. Egress is open until one is set
- Processes started by exec stop on a cold wake. Define a Service for anything that must answer the request that wakes the Sprite
- Create a checkpoint before a restore. Restoring replaces the filesystem, ends active sessions and keeps no copy of the replaced state
- Sprite creation is limited to 10 a minute on pay-as-you-go. The Go SDK reads `Retry-After` and the error code `sprite_creation_rate_limited` on a 429
- Delete Sprites you no longer need. An idle Sprite still bills cold storage for the bytes it holds

## 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.