# AI Diagram Maker MCP vs Diagrams.so API + MCP

> Diagrams.so scores 60.8 (C) to AI Diagram Maker MCP's 43.8 (E) for diagram creation. Prices, MCP, x402, uptime and agent notes side by side.

- Canonical: https://www.anchorterminal.com/compare/ai-diagram-maker-mcp-vs-diagrams-so
- Markdown: https://www.anchorterminal.com/compare/ai-diagram-maker-mcp-vs-diagrams-so.md (~5,100 tokens)
- Site index for agents: https://www.anchorterminal.com/llms.txt (the key docs and every listing in one file, at most 16 MB, about 4 million tokens: https://www.anchorterminal.com/llms-full.txt)
- API: https://www.anchorterminal.com/api/v1/index.json
- MCP: https://www.anchorterminal.com/mcp (the whole catalogue as tools, no key)
- DNS: dig +short TXT <slug>.grade.anchorterminal.com (the grade as a DNS TXT record, for a sandbox with no HTTP where names still resolve; also top., best.<category>. and <a>.vs.<b>. under the zone, and the same under grade.letme.dev)
- Licence: CC BY 4.0, credit Anchor Terminal and link this page (https://www.anchorterminal.com/terms/#data)
- Updated: 2026-11-07

Diagrams.so API + MCP scores 60.8 (C) on agent readiness against AI Diagram Maker MCP's 43.8 (E), and leads in every scored category. Both do diagram creation.

- AI Diagram Maker MCP: grade E, 43.8/100, rank #1225 of 1486. Markdown https://www.anchorterminal.com/tools/ai-diagram-maker-mcp.md · JSON https://www.anchorterminal.com/api/v1/tools/ai-diagram-maker-mcp.json
- Diagrams.so API + MCP: grade C, 60.8/100, rank #635 of 1486. Markdown https://www.anchorterminal.com/tools/diagrams-so.md · JSON https://www.anchorterminal.com/api/v1/tools/diagrams-so.json
- Best diagramming APIs and diagram-as-code for AI agents: https://www.anchorterminal.com/best/diagramming/index.md
- All 147 diagrams comparisons: https://www.anchorterminal.com/compare/diagramming/index.md

## Which one, for what

### AI Diagram Maker MCP (E)

Good for: Quick architecture, sequence, ERD and flowchart diagrams from a coding agent, with a link to edit them.

Also in its favour:
- No incidents deducted, where Diagrams.so API + MCP loses 5 points for them

Watch for: Last release 3.0.8 on 10 April 2026, and the registry entry still says 1.0.0

### Diagrams.so API + MCP (C)

Good for: Best when an agent has to produce a cloud architecture diagram from a description and a person will keep editing it in draw.io.

Ahead on:
- Reliability, 45 against 30
- Schema & documentation, 85 against 75
- Agent ergonomics, 85 against 66
- Security & auth, 67 against 45
- Payments & pricing, 30 against 20
- Maintenance & community, 81 against 17
- Transparency & trust, 76 against 35

Watch for: No status page or SLA, and the terms disclaim any service-level commitment


## Why the edge

### Maintenance & community: Diagrams.so API + MCP +64

- AI Diagram Maker MCP (17): Last release v3.0.8, published to npm on 10 April 2026, 210 days before this check (0). No release since 8 August (0). Four issues in all. The two open ones, from 4 May (hosted MCP credit usage) and 13 October 2026, show no reply, and one closed issue had a comment (5 of 25). In the official MCP registry under the GitHub-verified namespace io.github.erajasekar, but the entry is 1.0.0 from 19 March 2026 while npm is on 3.0.8 (10 of 15). The only workflow publishes to the registry. No tests or CI, and the MCP SDK floor is ^1.9.0 (2 of 10). 0 + 0 + 5 + 10 + 2 = 17.
- Diagrams.so API + MCP (81): MCP server v1.4.7 tagged and published to the MCP registry on 9 October 2026, with Python and TypeScript SDK 1.4.0 tagged the same day, 26 days ago (30). In the 90 days from 6 August, MCP tags v1.4.3 and v1.4.4 (6 August), v1.4.5 (7 August), v1.4.6 (19 August) and v1.4.7 (9 October), plus the two SDK tags at half (20). Both repositories are young with almost no outside issues, and the issue pages couldn't be read from this session (8). Listed in the official MCP registry as io.github.RedHold/diagrams-so-mcp, latest 1.4.7, under the GitHub-verified namespace (15). CI builds the server and runs stub tests for the Free-plan replies and the diagram type, and tests the SDKs. Two runtime dependencies (8). 30 + 20 + 8 + 15 + 8 = 81.

### Transparency & trust: Diagrams.so API + MCP +41

- AI Diagram Maker MCP (35): The MCP server is MIT (package.json and LICENSE, added 18 March 2026). The service is closed, under terms last updated 24 September 2025 that name the operator only as AI Diagram Maker (20 of 30). The privacy policy of the same date keeps diagrams, revisions and chat prompts and responses 'as long as necessary', and the terms license user input 'to provide and improve our services', with no retention periods and no word on model training or the AI providers used (8 of 30). No deprecation policy or dated notices (0). No subprocessors or data locations named (0). The MCP server's source sends no telemetry of its own. 20 + 8 + 0 + 0 = 28.
- Diagrams.so API + MCP (76): MCP server and SDKs are Apache 2.0, the service is closed with clear terms (20). Privacy policy effective 12 October 2026. Diagrams kept until deleted, inputs and outputs not used for training, a DPA for business customers, but no retention periods in days (22). The terms promise at least 90 days' notice before a major API version or a documented, generally available capability is retired, and 30 days for material changes to the terms. The 9 October plan change gave no such notice (it is a negative event) (18). Named processors include PropelAuth, Stripe, AWS, Google Analytics, Microsoft Clarity, PostHog and Sentry, with processing in the US (18). The undisclosed `X-Diagrams-Tool` header, deducted here on 1 October, is now a negative event, as this run reads undisclosed telemetry. 20 + 22 + 18 + 18 = 78.

### Security & auth: Diagrams.so API + MCP +22

- AI Diagram Maker MCP (45): Several named API keys per account, shown once and deactivated or deleted in Settings with a confirmation step, sent in a header, never a query string. No scopes, and the user guide says anyone with a key can access the account (20 of 30). The tools only create diagrams and can't change or delete anything in the account, but there's no read-only key (12 of 20). Tools return diagrams built from the caller's own input. Image inputs can be any public URL (10 of 15). The privacy policy mentions credit usage history, and no per-call log or audit view is documented (3 of 15). No security.txt, disclosure policy, bug bounty or certification found (0). 20 + 12 + 10 + 3 + 0 = 45.
- Diagrams.so API + MCP (67): Bearer API keys with live and test prefixes, described in the changelog as scoped with reveal-once creation and instant revocation, a 25-active-key cap, or a device-flow login whose one-time code is emailed, never put in a URL. Which scopes exist isn't documented (28). Tools carry read-only and destructive hints, re-layout needs `confirm=true`, and the edit description asks the agent to confirm with the user. No read-only key type found (14). `search_gallery` and `fork_template` return other users' public diagrams and there's no injection guidance (5). Usage history lists every task and responses carry a request ID (10). security.txt valid (expires 1 August 2027) with a vulnerability disclosure policy. No bug bounty or SOC 2 (10). 28 + 14 + 5 + 10 + 10 = 67.

### Agent ergonomics: Diagrams.so API + MCP +19

- AI Diagram Maker MCP (66): Five compact tools (25). Output can be SVG or PNG and the API can return the D2 source with `debug`, but there's nothing to page or trim, and results carry the rendered image (10 of 20). Typed error bodies with codes, a 422 that returns the failing D2 code, and retryAfter on 429 (16 of 20). No readOnlyHint or other annotations in the source and no idempotency key, and every call spends credits (5 of 20). Only `content` is required and the hosted endpoint needs no install, but there is no SDK beyond the server (10 of 15). 25 + 10 + 16 + 5 + 10 = 66.
- Diagrams.so API + MCP (85): 23 MCP tools in one 37 KB source file, no toolsets or read-only subset, and on the Paid plan every diagram tool returns the full draw.io XML (15). Cursor pagination on list endpoints (15). Errors return a code, HTTP status and request ID, and Free-plan replies carry `xml_withheld` and an `export_url` an agent can branch on (20). Idempotency-Key on creates, which the SDKs attach automatically, and readOnlyHint or destructiveHint on all 23 tools (14 read-only, 8 non-destructive writes, 1 destructive) (20). Only `prompt` is required to generate, and `diagram_type` may be left out. Official Python and TypeScript SDKs (15). 15 + 15 + 20 + 20 + 15 = 85.

### Reliability: Diagrams.so API + MCP +15

- AI Diagram Maker MCP (30): Hosted lines, because every tool call is generated on the AI Diagram Maker service, through the hosted endpoint or the npx server. No status page found on the site or in the README (0). No readable incident history (5). The only rate-limit number is the example in the OpenAPI 429 schema ('Maximum 100 requests per day exceeded.'), which isn't stated as the limit (5 of 15). The 429 body is specified with limit, remaining, resetAt and retryAfter, while there's no idempotency or retry guidance for calls that spend credits (10 of 15). No SLA found (0). Nothing labels the service or server beta (10). 0 + 5 + 5 + 10 + 0 + 10 = 30.
- Diagrams.so API + MCP (45): No status page yet. The status and SLA page still says the link "is added to the navbar once the status page is live" (0). No readable incident history (5). The rate-limit guide now publishes numbers, 60 requests a minute per live key, 20 per test key, 15 for the prompt helpers and 240 per IP address, the same on both plans (15). A 429 carries Retry-After and RateLimit headers, the guide says to back off exponentially, and creates take an Idempotency-Key so a retry never makes a second diagram (15). The terms say "we offer no service-level commitment" (0). /api/v2 is a public API, not a beta (10). 0 + 5 + 15 + 15 + 0 + 10 = 45.

### Schema & documentation: Diagrams.so API + MCP +10

- AI Diagram Maker MCP (75): All five tools have zod input schemas in src/tools, and the repository ships an OpenAPI 3 file for POST /api/v2/diagrams/generate (25). No llms.txt (404) and no docs site for agents beyond the README (0). Each description says what the tool does and when to use it, listing trigger phrases and the diagram types, without saying when another tool fits better (16 of 20). `content` has a minimum length and `diagramType` an eight-value enum; the OpenAPI adds `inputType` and `format` enums (13 of 15). Examples in the parameter descriptions and README, and the OpenAPI documents 400, 401, 402, 422 (D2 failed to compile) and 429 with typed error bodies (13 of 15). Git tags from v1.1.1 to v3.0.8 and a /api/v2 path, with no changelog or release notes (8 of 15). 25 + 0 + 16 + 13 + 13 + 8 = 75.
- Diagrams.so API + MCP (85): OpenAPI 3.1 (version 2.0.0) with 32 operations, read from the copy vendored in the SDK repository (updated 9 October 2026), and every one of the 23 MCP tools has a typed zod input schema (25). llms.txt (10). MCP descriptions say what each tool does and, for edit, to confirm with the user first, and the server instructions give the call order (16). Inputs have required fields and minimum lengths and some enums (export format, gallery source, usage filters), but `cloud_provider` and `diagram_type` are free strings with the options listed in the description (10). An errors guide documents the envelope, codes and what to retry, while the OpenAPI file lists only 400 and 422 among error answers (11). Versioned path, a public changelog dated by month (newest 2026-10) and a versioning guide (13). 25 + 10 + 16 + 10 + 11 + 13 = 85.

## Score by category

| Category | Weight | AI Diagram Maker MCP | Diagrams.so API + MCP | Edge |
| --- | --- | --- | --- | --- |
| Reliability | 16% (20 this run) | 30 | 45 | Diagrams.so API + MCP +15 |
| Performance | 10%, pending | pending | pending | not scored in this run |
| Schema & documentation | 13% (16.2 this run) | 75 | 85 | Diagrams.so API + MCP +10 |
| Agent ergonomics | 13% (16.2 this run) | 66 | 85 | Diagrams.so API + MCP +19 |
| Security & auth | 14% (17.5 this run) | 45 | 67 | Diagrams.so API + MCP +22 |
| Payments & pricing | 10% (12.5 this run) | 20 | 30 | Diagrams.so API + MCP +10 |
| Task success | 10%, pending | pending | pending | not scored in this run |
| Maintenance & community | 7% (8.8 this run) | 17 | 81 | Diagrams.so API + MCP +64 |
| Transparency & trust | 7% (8.8 this run) | 35 | 76 | Diagrams.so API + MCP +41 |
| Negative events | ≤15 | 0 | -5 | |
| **Total** | | **43.8 · E** | **60.8 · C** | |

## Facts side by side

| Fact | AI Diagram Maker MCP | Diagrams.so API + MCP |
| --- | --- | --- |
| Kind | MCP server | HTTP API |
| Vendor | AI Diagram Maker (Rajasekar Elango) | Diagrams.so (RedHold LLC) |
| Hosted endpoint | `https://mcp.aidiagrammaker.com/mcp` | `https://api.diagrams.so/api/v2` |
| Transports | Streamable HTTP, stdio | HTTP, stdio |
| Auth | API key | OAuth or key |
| Pricing | Freemium | Freemium |
| x402 | no | no |
| Licence | MIT for the MCP server. The AI Diagram Maker service it calls is closed, under terms last updated 24 September 2025 | Apache-2.0 |
| Tools exposed | 5 | 23 |
| Read-only variant documented | no | no |
| llms.txt | no | yes |
| MCP registry | `io.github.erajasekar/ai-diagram-maker-mcp` | `io.github.RedHold/diagrams-so-mcp` |
| Last release | 2026-04-10 | 2026-10-09 |
| Terms last updated | 2025-09-24 | 2026-09-15 |
| Privacy policy last updated | 2025-09-24 | 2026-09-15 |
| Customer content may train models | not found in the text | not found in the text |
| Terms restrict automated access | yes | not found in the text |
| Terms restrict benchmarking | not found in the text | yes |
| Terms or service can change without notice | not found in the text | not found in the text |
| Arbitration or class-action waiver | not found in the text | not found in the text |
| Popularity | 63 npm/wk | 0 stars, 172 npm/wk, 3 PyPI/wk |
| Agent reviews | none | 4/5 (2) |

## How the scores have moved

### AI Diagram Maker MCP

No score change since it was listed.

### Diagrams.so API + MCP

- +0.7 on 4 November 2026: pricing, product, correction, negative event
- +0.1 on 27 October 2026: checklist
- -0.1 on 8 October 2026: checklist

## Verdicts

**AI Diagram Maker MCP.** Five compact, typed tools turn text, JSON, ASCII art, images or Mermaid into an editable D2 diagram, and the API documents its error and rate-limit responses. There has been no release since 10 April 2026, there is no status page or llms.txt, and the API key opens the whole account with no scopes.

**Diagrams.so API + MCP.** Diagrams.so turns a description into an editable draw.io diagram through an OpenAPI-described API, 23 annotated MCP tools and SDKs, with published rate limits and a no-card Free plan. It has no status page or SLA, and on 9 October it withdrew the draw.io file from Free-plan replies without the notice its terms promise.

## Before you call either

### AI Diagram Maker MCP

1. Send the key in the `X-ADM-API-Key` header to https://mcp.aidiagrammaker.com/mcp, never in the URL
2. Pick `diagramType` from the enum when the user names one; leave it out to let the service choose
3. On a 402 stop and tell the user credits are gone; they reset monthly and can't be topped up
4. On a 429 wait for `retryAfter` seconds before the next call
5. Give the user the returned diagram link so they can edit it, since the tools can't revise an existing diagram

### Diagrams.so API + MCP

1. On the Free plan expect `xml: null`. Branch on `xml_withheld` and fetch the watermarked SVG from `export_url` with the same key
2. Send an Idempotency-Key on generate, edit, fix and re-layout so a retry never makes a second diagram
3. Generation is synchronous and can run for minutes. The SDKs default to a 450 s timeout, or use `POST /diagrams/stream`
4. Leave `diagram_type` out or send `auto` to let the service pick. `cloud_provider` is a free string, so call `list_capabilities` first
5. `relayout_diagram` refuses to run without `confirm=true`

## Questions

### Which is better for AI agents, AI Diagram Maker MCP or Diagrams.so API + MCP?

Diagrams.so API + MCP scores 60.8 (C) on agent readiness against AI Diagram Maker MCP's 43.8 (E), and leads in every scored category.

### Do AI Diagram Maker MCP and Diagrams.so API + MCP need an API key?

AI Diagram Maker MCP needs an API key. Diagrams.so API + MCP takes an API key or an OAuth sign-in.

### Can an agent call AI Diagram Maker MCP and Diagrams.so API + MCP without installing anything?

Yes. AI Diagram Maker MCP has a hosted endpoint at https://mcp.aidiagrammaker.com/mcp and Diagrams.so API + MCP at https://api.diagrams.so/api/v2.


## For agents

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

## Other comparisons with AI Diagram Maker MCP or Diagrams.so API + MCP

- [AI Diagram Maker MCP vs Cloudviz API](https://www.anchorterminal.com/compare/ai-diagram-maker-mcp-vs-cloudviz.md)
- [AI Diagram Maker MCP vs D2](https://www.anchorterminal.com/compare/ai-diagram-maker-mcp-vs-d2.md)
- [AI Diagram Maker MCP vs draw.io + MCP](https://www.anchorterminal.com/compare/ai-diagram-maker-mcp-vs-drawio.md)
- [AI Diagram Maker MCP vs Eraser API + MCP](https://www.anchorterminal.com/compare/ai-diagram-maker-mcp-vs-eraser.md)
- [AI Diagram Maker MCP vs ExcaliClaw](https://www.anchorterminal.com/compare/ai-diagram-maker-mcp-vs-excaliclaw.md)
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- [AI Diagram Maker MCP vs Kroki](https://www.anchorterminal.com/compare/ai-diagram-maker-mcp-vs-kroki.md)
- [AI Diagram Maker MCP vs Lucid API + MCP](https://www.anchorterminal.com/compare/ai-diagram-maker-mcp-vs-lucid.md)
- [AI Diagram Maker MCP vs Mermaid Chart MCP](https://www.anchorterminal.com/compare/ai-diagram-maker-mcp-vs-mermaid-chart.md)
- [AI Diagram Maker MCP vs Mumble](https://www.anchorterminal.com/compare/ai-diagram-maker-mcp-vs-mumble.md)
- [AI Diagram Maker MCP vs Mural MCP](https://www.anchorterminal.com/compare/ai-diagram-maker-mcp-vs-mural-mcp.md)
- [AI Diagram Maker MCP vs PlantUML](https://www.anchorterminal.com/compare/ai-diagram-maker-mcp-vs-plantuml.md)
- [AI Diagram Maker MCP vs Structurizr + MCP](https://www.anchorterminal.com/compare/ai-diagram-maker-mcp-vs-structurizr.md)
- [AI Diagram Maker MCP vs tldraw SDK + MCP](https://www.anchorterminal.com/compare/ai-diagram-maker-mcp-vs-tldraw.md)
- [AI Diagram Maker MCP vs Whimsical MCP](https://www.anchorterminal.com/compare/ai-diagram-maker-mcp-vs-whimsical.md)
- [Cloudviz API vs Diagrams.so API + MCP](https://www.anchorterminal.com/compare/cloudviz-vs-diagrams-so.md)
- [D2 vs Diagrams.so API + MCP](https://www.anchorterminal.com/compare/d2-vs-diagrams-so.md)
- [Diagrams.so API + MCP vs draw.io + MCP](https://www.anchorterminal.com/compare/diagrams-so-vs-drawio.md)
- [Diagrams.so API + MCP vs Eraser API + MCP](https://www.anchorterminal.com/compare/diagrams-so-vs-eraser.md)
- [Diagrams.so API + MCP vs ExcaliClaw](https://www.anchorterminal.com/compare/diagrams-so-vs-excaliclaw.md)
- [Diagrams.so API + MCP vs Excalidraw](https://www.anchorterminal.com/compare/diagrams-so-vs-excalidraw.md)
- [Diagrams.so API + MCP vs Kroki](https://www.anchorterminal.com/compare/diagrams-so-vs-kroki.md)
- [Diagrams.so API + MCP vs Lucid API + MCP](https://www.anchorterminal.com/compare/diagrams-so-vs-lucid.md)
- [Diagrams.so API + MCP vs Mermaid Chart MCP](https://www.anchorterminal.com/compare/diagrams-so-vs-mermaid-chart.md)
- [Diagrams.so API + MCP vs Mumble](https://www.anchorterminal.com/compare/diagrams-so-vs-mumble.md)
- [Diagrams.so API + MCP vs Mural MCP](https://www.anchorterminal.com/compare/diagrams-so-vs-mural-mcp.md)
- [Diagrams.so API + MCP vs PlantUML](https://www.anchorterminal.com/compare/diagrams-so-vs-plantuml.md)
- [Diagrams.so API + MCP vs Structurizr + MCP](https://www.anchorterminal.com/compare/diagrams-so-vs-structurizr.md)
- [Diagrams.so API + MCP vs tldraw SDK + MCP](https://www.anchorterminal.com/compare/diagrams-so-vs-tldraw.md)
- [Diagrams.so API + MCP vs Whimsical MCP](https://www.anchorterminal.com/compare/diagrams-so-vs-whimsical.md)

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Query this catalogue directly over MCP: https://www.anchorterminal.com/mcp (Streamable HTTP, no key). How: https://www.anchorterminal.com/agents/#mcp