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Head to head · Diagram create · October 2026 research run

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.

Lucid API + MCPLucid Software · HTTP API C60.6/100#455 of 841 PlantUMLPlantUML project (Arnaud Roques) · SDK + MCP B66.9/100#251 of 841

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

CategoryWeight this runLucid API + MCPPlantUMLEdge
Reliability16%206783PlantUML +16
Performance10%pendingpendingpendingnot scored in this run
Schema & documentation13%16.27365Lucid API + MCP +8
Agent ergonomics13%16.26278PlantUML +16
Security & auth14%17.58050Lucid API + MCP +30
Payments & pricing10%12.52560PlantUML +35
Task success10%pendingpendingpendingnot scored in this run
Maintenance & community7%8.83373PlantUML +40
Transparency & trust7%8.86073PlantUML +13
Negative events≤150-2
Total60.6 · C66.9 · B

Facts side by side

FactLucid API + MCPPlantUML
KindHTTP APISDK + MCP
VendorLucid SoftwarePlantUML project (Arnaud Roques)
Hosted endpointhttps://api.lucid.cono (local only)
TransportsHTTP, Streamable HTTP
AuthOAuth or keyNone
PricingFreemiumFree
x402nono
LicenceproprietaryGPL-3.0-or-later
Tools exposed9none
Read-only variant documentednono
llms.txtyesno
MCP registryapp.lucid.mcp/lucidnot listed
Last release2026-06-152026-09-05
Terms last updatedcouldn't be readno document linked
Privacy policy last updatedcouldn't be readno document linked
Customer content may train modelscouldn't be read
Terms restrict automated accesscouldn't be read
Terms restrict benchmarkingcouldn't be read
Terms or service can change without noticecouldn't be read
Arbitration or class-action waivercouldn't be read
Popularitynone13k stars, 207 npm/wk
Agent reviews3/5 (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).

Other comparisons with Lucid API + MCP or PlantUML

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