D2

# Fix list: D2

From Anchor Terminal's listing at https://www.anchorterminal.com/tools/d2, the October 2026 research run, assessed 8 October 2026. Grade B, 65.3 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 D2: 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, 48 out of 100, up to 9.1 more on the total

Why it scored 48: No credential exists to leak or scope (20). The CLI runs with the owner's file and network rights. Release 0.9.0 reads local imports and fetches remote images when bundling, and the private-network block and rooted file policy sit unreleased on the default branch. `--bundle=false` avoids fetches (8). The tool renders the caller's own text and returns no third-party content (10). `--debug` logs only (3). No SECURITY.md, security.txt or published advisories. Release archives carry checksums, signed provenance and SBOM attestations, CI actions are pinned by hash, and about 30 hardening pull requests merged on 11 and 12 September 2026 (7).

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. Reliability, 68 out of 100, up to 6.4 more on the total

Why it scored 68: Read with the local-software lines, because D2 runs on the owner's machine. Install script, Homebrew, release archives for six platforms, Docker and npm, with macOS 13 and Go 1.27 stated (20). The `ci` workflow passed on the last four pushes to the default branch, the latest on 2 October 2026, and the repository holds 497 Go test files (25). GitHub counts 535 open issues and pull requests, and the five outside issues opened since 13 September have no reply (12). Release notes exist for each version and warn of layout changes, though versions are 0.x and we found no note for the Go import path moving to `github.com/d2lang/d2` (11). The latest release is 0.9.0, and the maintainer lists a stable 1.0 as a goal (0).

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.

## 3. Schema & documentation, 65 out of 100, up to 5.7 more on the total

Why it scored 65: Read as a CLI and library. No OpenAPI or formal grammar, and the maintainer names a formalised grammar as future work. The contract is a man page, typed Go packages and TypeScript signatures in d2.js (12). No llms.txt (HTTP 404), though the docs are Markdown in a public repository (3). The tour covers each language construct on its own page, and the man page describes every flag with its default (15). Flags are typed with defaults and environment variables, and d2.js lists its compile and render options (10). Examples on every tour page plus runnable Go examples, with no catalogue of compiler errors (10). Release notes for every version on the docs site and a separate d2.js changelog (15).

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. Payments & pricing, 60 out of 100, up to 5 more on the total

Why it scored 60: Read with the self-hosted rule. Free MPL-2.0 software with nothing to buy and no payment protocol (0). No price to publish (20). No card or trial needed (20). An agent can install and run it with no signup (20).

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.

## 5. Agent ergonomics, 78 out of 100, up to 3.6 more on the total

Why it scored 78: One command with text in and a diagram out, and no tool definitions to load (22). `--target` renders one board, `--scale` sizes the output and ASCII output suits a text-only reader (14). `d2 validate` and `d2 fmt --check` report problems before rendering, and the man page tells callers to rely on the exit status. No list of error codes (13). Rendering is a pure function of the input for Dagre and ELK, TALA is seeded, and `d2oracle` returns new graphs instead of mutating. A partial file can be written on error (15). `d2 in.d2` works with no flags, and official libraries exist for Go and JavaScript (14).

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.

## 6. Transparency & trust, 69 out of 100, up to 2.7 more on the total

Made of editorial 74, provenance 63.

Why it scored 69: MPL-2.0 for the language, the renderers and TALA (30). No privacy policy, and the software runs locally. The FAQ says the CLI uses no network after install apart from a version check, and the playground runs in the browser through WebAssembly (18). Release notes mark deprecated Go and d2.js entry points as callable for one more release, and the `@terrastruct/d2` package and `terrastruct/d2` image stay as mirrors, with no dates given (12). The FAQ states there is no telemetry. We found no documented switch for the version check (14).

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: d2lang.com, registered 2022-10-24 (3 years) (7 of 15)
- Status page: not found (0 of 10)
- security.txt: not found (0 of 10)

## 7. Maintenance & community, 74 out of 100, up to 2.3 more on the total

Why it scored 74: Release 0.9.0 on 7 September 2026, 31 days before the check (20). Four tagged versions since 10 July, 0.8.0 and 0.8.1 on 6 August, 0.8.2 on 24 August and 0.9.0 (20). All 317 commits since 8 July are by one maintainer, who wrote on 5 September that his time is limited, and outside issues opened since 13 September have no reply (10). The Go library and `@d2lang/d2` 0.1.34 match 0.9.0 (15). Go 1.27, dependencies refreshed in 0.8.2 and CI on every push (9).

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.

- Whether the version check the FAQ describes still exists. A search of the CLI source found no call to GitHub, and no opt-out is documented
- Whether the Go import path change from `oss.terrastruct.com/d2` to `github.com/d2lang/d2` was announced. Release notes for 0.8.0 and 0.8.1 are not in the repository, and the notes for 0.8.2 and 0.9.0 do not mention it
- Which legal entity now holds the copyright. LICENSE.txt names Terrastruct Inc., and the sponsor page names The Hack Foundation as fiscal sponsor
- How many of the 535 open items are crash or regression reports. Only the 30 newest issues and pull requests were read
- unchecked: d2studio.ai, the editor that app.terrastruct.com redirects to. It is a separate product and was not read
- The lead named Terrastruct as vendor. Terrastruct is shutting down and the project is now under The Hack Foundation

## Weaknesses

- No 1.0 release. The maintainer lists a stable 1.0 with a formal grammar as a goal, and 0.8.2 changed Dagre and ELK layout output
- Terrastruct, the company that built D2, is shutting down. The project is now donation-funded under The Hack Foundation
- All 317 commits since 8 July 2026 are by one maintainer, who says his time on D2 is limited
- A security hardening pass merged on 11 and 12 September 2026 is not in a release yet, and the repository has no security policy
- No llms.txt, no machine-readable grammar and no MCP server. The maintainer rules out an MCP server and a hosted API

## 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.

- Check the exit status of `d2`, never the output file. The man page says a partial render can be written when an error occurs
- Run `d2 validate file.d2` before rendering, and `d2 fmt` to normalise the source
- Pass `-` for input and output and set `--stdout-format` (svg, png, ascii, txt, pdf, pptx or gif) to work without files
- Use `--stdout-format ascii` when the reader is a text-only model
- Pass `--bundle=false` or review image URLs and imports before rendering D2 text from an untrusted source. Release 0.9.0 fetches remote images when bundling

## 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.