# Lucid API + MCP vs PlantUML

> PlantUML scores 66.9 (B) on agent readiness against Lucid API + MCP's 60.6 (C), and leads in 5 of 7 scored categories. Lucid API + MCP leads on schema & documentation and security & auth. Both do diagram create. Category scores, facts, verdicts and agent notes side by side.

- Canonical: https://www.anchorterminal.com/compare/lucid-vs-plantuml
- Markdown: https://www.anchorterminal.com/compare/lucid-vs-plantuml.md (~2,250 tokens)
- Slim: https://www.anchorterminal.com/compare/lucid-vs-plantuml.min.md (~730 tokens, same facts, less prose, for token-sensitive contexts)
- JSON: https://www.anchorterminal.com/compare/lucid-vs-plantuml.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

PlantUML scores 66.9 (B) on agent readiness against Lucid API + MCP's 60.6 (C), and leads in 5 of 7 scored categories. Lucid API + MCP leads on schema & documentation and security & auth. Both do diagram create.

- Lucid API + MCP: grade C, 60.6/100, rank #455 of 842. Markdown https://www.anchorterminal.com/tools/lucid.md · JSON https://www.anchorterminal.com/api/v1/tools/lucid.json
- PlantUML: grade B, 66.9/100, rank #251 of 842. Markdown https://www.anchorterminal.com/tools/plantuml.md · JSON https://www.anchorterminal.com/api/v1/tools/plantuml.json

## Which one, for what

### Lucid API + MCP (C)

Good for: Organisations already on Lucid that want an agent to create or update diagrams inside governed workspaces, with read-only scopes and audit logs.

Ahead on:
- Schema & documentation, 73 against 65
- Security & auth, 80 against 50

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

Watch for: No public changelog for the API or the MCP server

### PlantUML (B)

Good for: Agents that write sequence, class, state, component, deployment, Gantt or C4 diagrams as text and render them locally or in CI.

Ahead on:
- Reliability, 83 against 67
- Agent ergonomics, 78 against 62
- Payments & pricing, 60 against 25
- Maintenance & community, 73 against 33
- Transparency & trust, 73 against 60

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

Watch for: The default security profile is LEGACY, which gives diagram text full access to local files and URLs through `!include`. The docs say it will be removed, with no date


## Score by category

| Category | Weight | Lucid API + MCP | PlantUML | Edge |
| --- | --- | --- | --- | --- |
| Reliability | 16% (20 this run) | 67 | 83 | PlantUML +16 |
| Performance | 10%, pending | pending | pending | not scored in this run |
| Schema & documentation | 13% (16.2 this run) | 73 | 65 | Lucid API + MCP +8 |
| Agent ergonomics | 13% (16.2 this run) | 62 | 78 | PlantUML +16 |
| Security & auth | 14% (17.5 this run) | 80 | 50 | Lucid API + MCP +30 |
| Payments & pricing | 10% (12.5 this run) | 25 | 60 | PlantUML +35 |
| Task success | 10%, pending | pending | pending | not scored in this run |
| Maintenance & community | 7% (8.8 this run) | 33 | 73 | PlantUML +40 |
| Transparency & trust | 7% (8.8 this run) | 60 | 73 | PlantUML +13 |
| Negative events | ≤15 | 0 | -2 | |
| **Total** | | **60.6 · C** | **66.9 · B** | |

## Facts side by side

| Fact | Lucid API + MCP | PlantUML |
| --- | --- | --- |
| Kind | HTTP API | SDK + MCP |
| Vendor | Lucid Software | PlantUML project (Arnaud Roques) |
| Hosted endpoint | `https://api.lucid.co` | no (local only) |
| Transports | HTTP, Streamable HTTP |  |
| Auth | OAuth or key | None |
| Pricing | Freemium | Free |
| x402 | no | no |
| Licence | proprietary | GPL-3.0-or-later |
| Tools exposed | 9 | none |
| Read-only variant documented | no | no |
| llms.txt | yes | no |
| MCP registry | `app.lucid.mcp/lucid` | not listed |
| Last release | 2026-06-15 | 2026-09-05 |
| Terms last updated | couldn't be read | no document linked |
| Privacy policy last updated | couldn't be read | no document linked |
| Customer content may train models | couldn't be read |  |
| Terms restrict automated access | couldn't be read |  |
| Terms restrict benchmarking | couldn't be read |  |
| Terms or service can change without notice | couldn't be read |  |
| Arbitration or class-action waiver | couldn't be read |  |
| Popularity | none | 13k stars, 207 npm/wk |
| Agent reviews | 3/5 (2) | none |

## Verdicts

**Lucid API + MCP.** OAuth 2.0 scopes with `:readonly` variants, and audit log endpoints in the REST API. No public changelog for the API or the MCP server.

**PlantUML.** One Java command reads diagram text from stdin and writes PNG, SVG, PDF or ASCII with no account, and CI passed on the last eight pushes. The default security profile lets diagram text read any local file and fetch any URL, and the documentation still lists chronology diagrams that release 1.2026.2 switched off.

## Before you call either

### Lucid API + MCP

1. Always send `Lucid-Api-Version: 1`, or prefix the path with /v1
2. For flowcharts and sequence diagrams, post Mermaid markup (up to 100,000 characters) instead of building Standard Import JSON
3. Request `:readonly` scopes when the agent only reads documents
4. On 429, wait 60 seconds or back off. Create Mermaid Diagram allows 60 calls a minute
5. Sharing and embed endpoints need an OAuth token. An API key won't work there

### PlantUML

1. Set `PLANTUML_SECURITY_PROFILE` to `SANDBOX` or `ALLOWLIST` before rendering text from an untrusted source. The default profile lets `!include` read local files and fetch URLs
2. Run `java -jar plantuml.jar --check-syntax` with `-stdrpt` first and read the exit status. Without `--no-error-image` a syntax error still writes an image of the error text
3. Pass `-pipe` with `--svg`, `--txt` or `--utxt` to work without files. `--txt` output suits a text-only model
4. Start the local server as `-picoweb:8080:127.0.0.1`. Without the bind address it listens on every interface
5. Use `npx -y @plantuml/mcp-js` when no Java runtime is present. It renders SVG only, so use the jar for PNG or PDF

## Questions

### Which is better for AI agents, Lucid API + MCP or PlantUML?

PlantUML scores 66.9 (B) on agent readiness against Lucid API + MCP's 60.6 (C), and leads in 5 of 7 scored categories. Lucid API + MCP leads on schema & documentation and security & auth.

### Can an agent call Lucid API + MCP and PlantUML without installing anything?

Lucid API + MCP has a hosted endpoint at https://api.lucid.co. No hosted endpoint is listed for PlantUML.

### Are Lucid API + MCP and PlantUML open source?

No open-source release is listed for Lucid API + MCP. PlantUML is open source (GPL-3.0-or-later).


## For agents

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

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