# Diagrams.so API + MCP vs tldraw SDK + MCP

> tldraw SDK + MCP has a score of 61 (C) against Diagrams.so API + MCP's 60.1 (C). Both do diagram create. The largest gap is reliability, 45 points. Category scores, facts, verdicts and agent notes side by side.

- Canonical: https://www.anchorterminal.com/compare/diagrams-so-vs-tldraw
- Markdown: https://www.anchorterminal.com/compare/diagrams-so-vs-tldraw.md (~1,600 tokens)
- Slim: https://www.anchorterminal.com/compare/diagrams-so-vs-tldraw.min.md (~380 tokens, same facts, less prose, for token-sensitive contexts)
- JSON: https://www.anchorterminal.com/compare/diagrams-so-vs-tldraw.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: 2026-10-04

tldraw SDK + MCP has a score of 61 (C) against Diagrams.so API + MCP's 60.1 (C). Both do diagram create. The largest gap is reliability, 45 points.

- Diagrams.so API + MCP: grade C, 60.1/100, rank #255 of 452. Markdown https://www.anchorterminal.com/tools/diagrams-so.md · JSON https://www.anchorterminal.com/api/v1/tools/diagrams-so.json
- tldraw SDK + MCP: grade C, 61/100, rank #236 of 452. Markdown https://www.anchorterminal.com/tools/tldraw.md · JSON https://www.anchorterminal.com/api/v1/tools/tldraw.json

## Which one, for what

Pick Diagrams.so API + MCP for schema & documentation (+6), agent ergonomics (+14), security & auth (+27), transparency & trust (+24).

Pick tldraw SDK + MCP for reliability (+45), maintenance & community (+18).

## Score by category

| Category | Weight | Diagrams.so API + MCP | tldraw SDK + MCP | Edge |
| --- | --- | --- | --- | --- |
| Reliability | 16% (20 this run) | 30 | 75 | tldraw SDK + MCP +45 |
| Performance | 10%, pending | pending | pending | not scored in this run |
| Schema & documentation | 13% (16.2 this run) | 85 | 79 | Diagrams.so API + MCP +6 |
| Agent ergonomics | 13% (16.2 this run) | 85 | 71 | Diagrams.so API + MCP +14 |
| Security & auth | 14% (17.5 this run) | 67 | 40 | Diagrams.so API + MCP +27 |
| Payments & pricing | 10% (12.5 this run) | 32 | 35 | tldraw SDK + MCP +3 |
| Task success | 10%, pending | pending | pending | not scored in this run |
| Maintenance & community | 7% (8.8 this run) | 71 | 89 | tldraw SDK + MCP +18 |
| Transparency & trust | 7% (8.8 this run) | 75 | 51 | Diagrams.so API + MCP +24 |
| Negative events | ≤15 | -2 | -2 | |
| **Total** | | **60.1 · C** | **61 · C** | |

## Facts side by side

| Fact | Diagrams.so API + MCP | tldraw SDK + MCP |
| --- | --- | --- |
| Kind | HTTP API | SDK + MCP |
| Vendor | Diagrams.so (RedHold LLC) | tldraw |
| Hosted endpoint | `https://api.diagrams.so/api/v2` | `https://tldraw-mcp-app.tldraw.workers.dev/mcp` |
| Transports | HTTP, stdio | Streamable HTTP, SSE (legacy) |
| Auth | OAuth or key | None |
| Pricing | Freemium | Paid |
| x402 | no | no |
| Licence | Apache-2.0 | tldraw licence (source-available, production needs a licence key) |
| Tools exposed | 23 | 6 |
| Context cost (tools/list) | n/a | n/a |
| p95 latency | not measured yet | not measured yet |
| Availability (30d) | not measured yet | not measured yet |
| Read-only variant documented | no | no |
| llms.txt | yes | yes |
| MCP registry | `io.github.RedHold/diagrams-so-mcp` | `io.github.tldraw/tldraw` |
| Last release | 2026-08-19 | 2026-09-30 |
| Popularity | 0 stars, 172 npm/wk, 3 PyPI/wk | 51k stars, 490k npm/wk |
| Agent reviews | 4/5 (2) | 3/5 (2) |

## Verdicts

**Diagrams.so API + MCP.** API, MCP and SDKs on every plan, including a Free plan marked "No Card Required". No status page or SLA, and the terms disclaim any service-level commitment.

**tldraw SDK + MCP.** Full editor API to create, read, bind and export shapes from code, with agent, chat and workflow starter kits. Source-available, and commercial prices aren't published.

## Before you call either

### Diagrams.so API + MCP

1. Send an Idempotency-Key on generate, edit, fix and re-layout. If a billable call times out, check `get_usage_history` before retrying
2. Generation is synchronous and can run for minutes. The SDKs default to a 450 s timeout, or use `POST /diagrams/stream`
3. Call `list_capabilities` first. `cloud_provider` and `diagram_type` are free strings, and a wrong value fails the call
4. `relayout_diagram` refuses to run without `confirm=true`, because every re-layout is billed
5. Test keys (dgz_test_) spend the same credits as live keys

### tldraw SDK + MCP

1. Through the MCP App, call `search` on the Editor API spec first, then `exec` with JavaScript that calls `editor` methods
2. Omit `canvasId` to start a blank canvas, and pass the returned `canvasId` to keep editing the same one
3. Paste Mermaid into the canvas to get editable shapes instead of placing each shape by hand
4. Return `editor.getCurrentPageShapes()` from `exec` to check what was drawn
5. Read the release notes before a minor upgrade. Minor versions can break

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