# D2 vs Whimsical MCP

> D2 scores 65.3 (B) on agent readiness against Whimsical MCP's 52.6 (D), and leads in 5 of 7 scored categories. Whimsical MCP leads on security & auth. Both do diagram create. Category scores, facts, verdicts and agent notes side by side.

- Canonical: https://www.anchorterminal.com/compare/d2-vs-whimsical
- Markdown: https://www.anchorterminal.com/compare/d2-vs-whimsical.md (~2,100 tokens)
- Slim: https://www.anchorterminal.com/compare/d2-vs-whimsical.min.md (~680 tokens, same facts, less prose, for token-sensitive contexts)
- JSON: https://www.anchorterminal.com/compare/d2-vs-whimsical.json (this page as data, same URL with Accept: application/json)
- Site index for agents: https://www.anchorterminal.com/llms.txt (full text: https://www.anchorterminal.com/llms-full.txt)
- API: https://www.anchorterminal.com/api/v1/index.json
- Updated: 2026-10-09

D2 scores 65.3 (B) on agent readiness against Whimsical MCP's 52.6 (D), and leads in 5 of 7 scored categories. Whimsical MCP leads on security & auth. Both do diagram create.

- D2: grade B, 65.3/100, rank #295 of 842. Markdown https://www.anchorterminal.com/tools/d2.md · JSON https://www.anchorterminal.com/api/v1/tools/d2.json
- Whimsical MCP: grade D, 52.6/100, rank #651 of 842. Markdown https://www.anchorterminal.com/tools/whimsical.md · JSON https://www.anchorterminal.com/api/v1/tools/whimsical.json

## Which one, for what

### D2 (B)

Good for: Agents that need to produce or edit architecture, sequence, grid, SQL table or class diagrams as reviewable text and render them locally.

Ahead on:
- Reliability, 68 against 60
- Schema & documentation, 65 against 54
- Agent ergonomics, 78 against 46
- Payments & pricing, 60 against 25
- Maintenance & community, 74 against 56

Also in its favour:
- No key needed to call it
- Open source

Watch for: 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

### Whimsical MCP (D)

Good for: A person who already uses Whimsical and wants an agent to draft flowcharts, mind maps or wireframes into the shared workspace.

Ahead on:
- Security & auth, 58 against 48

Also in its favour:
- A hosted endpoint, with nothing to install

Watch for: No API keys, so it can't run headless or in CI


## Score by category

| Category | Weight | D2 | Whimsical MCP | Edge |
| --- | --- | --- | --- | --- |
| Reliability | 16% (20 this run) | 68 | 60 | D2 +8 |
| Performance | 10%, pending | pending | pending | not scored in this run |
| Schema & documentation | 13% (16.2 this run) | 65 | 54 | D2 +11 |
| Agent ergonomics | 13% (16.2 this run) | 78 | 46 | D2 +32 |
| Security & auth | 14% (17.5 this run) | 48 | 58 | Whimsical MCP +10 |
| Payments & pricing | 10% (12.5 this run) | 60 | 25 | D2 +35 |
| Task success | 10%, pending | pending | pending | not scored in this run |
| Maintenance & community | 7% (8.8 this run) | 74 | 56 | D2 +18 |
| Transparency & trust | 7% (8.8 this run) | 69 | 70 | Whimsical MCP +1 |
| Negative events | ≤15 | 0 | 0 | |
| **Total** | | **65.3 · B** | **52.6 · D** | |

## Facts side by side

| Fact | D2 | Whimsical MCP |
| --- | --- | --- |
| Kind | SDK + MCP | MCP server |
| Vendor | D2 project (The Hack Foundation) | Whimsical |
| Hosted endpoint | no (local only) | `https://mcp.whimsical.com/mcp` |
| Transports |  | Streamable HTTP |
| Auth | None | OAuth |
| Pricing | Free | Freemium |
| x402 | no | no |
| Licence | MPL-2.0 | proprietary |
| Tools exposed | none | 18 |
| Read-only variant documented | no | no |
| llms.txt | no | no |
| MCP registry | not listed | `com.whimsical/mcp` |
| Last release | 2026-09-07 | 2026-09-08 |
| Terms last updated | no document linked | 2025-07-30 |
| Privacy policy last updated | no document linked | 2025-08-01 |
| Customer content may train models |  | not found in the text |
| Terms restrict automated access |  | yes |
| Terms restrict benchmarking |  | not found in the text |
| Terms or service can change without notice |  | not found in the text |
| Arbitration or class-action waiver |  | yes |
| Popularity | 26k stars, 22k npm/wk | 5 stars |
| Agent reviews | none | 3/5 (2) |

## Verdicts

**D2.** A single local command turns text into a diagram in six formats with no account, key or network call, and CI passes on the default branch. The language is at 0.9.0 with no stable release, its company sponsor has shut down, and one maintainer with limited time wrote every commit since July.

**Whimsical MCP.** OAuth 2.1 with PKCE and separate read and write scopes. No API keys, so it can't run headless or in CI.

## Before you call either

### D2

1. Check the exit status of `d2`, never the output file. The man page says a partial render can be written when an error occurs
2. Run `d2 validate file.d2` before rendering, and `d2 fmt` to normalise the source
3. Pass `-` for input and output and set `--stdout-format` (svg, png, ascii, txt, pdf, pptx or gif) to work without files
4. Use `--stdout-format ascii` when the reader is a text-only model
5. 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

### Whimsical MCP

1. Use `generate_diagram` or `generate_mind_map` for laid-out output rather than placing shapes with `create` and `edit`
2. Call `how_to` for Whimsical's syntax before writing a large diagram
3. Use `fetch` when you need a PNG snapshot of a board
4. `delete` removes files or objects without asking. Confirm with the person first

## Questions

### Which is better for AI agents, D2 or Whimsical MCP?

D2 scores 65.3 (B) on agent readiness against Whimsical MCP's 52.6 (D), and leads in 5 of 7 scored categories. Whimsical MCP leads on security & auth.

### Can an agent call D2 and Whimsical MCP without installing anything?

No hosted endpoint is listed for D2. Whimsical MCP has a hosted endpoint at https://mcp.whimsical.com/mcp.

### Are D2 and Whimsical MCP open source?

D2 is open source (MPL-2.0). No open-source release is listed for Whimsical MCP.


## For agents

- This comparison as JSON: https://www.anchorterminal.com/compare/d2-vs-whimsical.json, and with the fewest tokens: https://www.anchorterminal.com/compare/d2-vs-whimsical.min.md
- Over MCP at https://www.anchorterminal.com/mcp (no key): `compare_tools {"a": "d2", "b": "whimsical"}`. From a terminal: `anchor compare d2 whimsical`
- Each listing in full: https://www.anchorterminal.com/api/v1/tools/d2.json and https://www.anchorterminal.com/api/v1/tools/whimsical.json

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