mermaid-mcp
Server Configuration
Describes the environment variables required to run the server.
| Name | Required | Description | Default |
|---|---|---|---|
| MERMAID_MMDC | No | Mermaid CLI command to use, e.g. `/opt/mmdc/node_modules/.bin/mmdc` | |
| MERMAID_CLI_PACKAGE | No | npx fallback package (default `@mermaid-js/mermaid-cli@12.0.0`) | @mermaid-js/mermaid-cli@12.0.0 |
| MERMAID_MCP_TIMEOUT | No | Seconds per mmdc run (default 120) | 120 |
| MERMAID_PUPPETEER_CONFIG | No | Puppeteer JSON passed to `mmdc -p`. Use `{"args": ["--no-sandbox"]}` when Chromium has no sandbox (root in Docker, GitHub Actions) |
Instructions
Guidance the server publishes about itself, which clients place ahead of the tool catalog so the model reads it before choosing anything.
This server publishes no instructions, or was last inspected before Glama recorded them.
Capabilities
Features and capabilities supported by this server
Protocol revision2025-11-25
| Capability | Details |
|---|---|
| tools | {
"listChanged": false
} |
| prompts | {
"listChanged": false
} |
| resources | {
"subscribe": false,
"listChanged": false
} |
| experimental | {} |
Tools
Functions exposed to the LLM to take actions
| Name | Description |
|---|---|
| from_irA | Convert diagram JSON IR to Mermaid source. Deterministic; fails on unknown kinds, missing fields, or undeclared ids. IR: {diagram, target, ...}; see list_ir_targets. |
| renderA | Validate and render a diagram with Mermaid CLI 12. Pass ir (preferred) or Mermaid source. Returns the Mermaid source plus PNG image (and SVG if requested). Fails on render errors. |
| list_ir_targetsA | List supported IR targets, or pass target to get that target's IR fields and example. |
Prompts
Interactive templates invoked by user choice
| Name | Description |
|---|---|
No prompts | |
Resources
Contextual data attached and managed by the client
| Name | Description |
|---|---|
No resources | |
TDQS
Scored across 3 tools
Each tool has a clearly distinct purpose: from_ir converts IR to Mermaid source, render produces images from source or IR, and list_ir_targets provides metadata about supported IR targets. There is no functional overlap that would cause an agent to misselect.
Tool names are all lowercase with underscores and generally readable. However, from_ir does not follow the verb-first pattern of render and list_ir_targets, creating a minor stylistic deviation that reduces full consistency.
At three tools, the server is tightly scoped to its stated IR-to-Mermaid rendering workflow. Each tool earns its place with a distinct responsibility, and the count is well within the typical 3-15 range.
The set covers the full pipeline: IR to source, source/IR to rendered image, and metadata lookup for IR targets. A slight gap is the absence of a source-to-IR conversion, but that is not implied by the server's purpose and can be worked around.