AI Diagram Maker MCP vs Mermaid Chart MCP

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.

Mermaid Chart MCP 32

Closed server. The 30 September check read typed tool inputs from an unauthenticated tools/list, which we couldn't repeat (15). mermaid.ai/llms.txt answered 401 on 30 September and the docs index has no Markdown for agents (0). The docs give one line for each of 9 tools, while the live server listed 25 on 30 September, including GitHub, Jira and Notion helpers with no docs (6). Input constraints unread (7). Setup examples, no documented errors (4). No changelog, and the registry entry hasn't changed since 18 September 2025 (0).

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.

Mermaid Chart MCP 53

The official TypeScript SDK, @mermaidchart/sdk 0.2.8, was tagged on 17 September 2026 (30). Two SDK releases since 3 July (0.2.7 on 31 July and 0.2.8) and no dated server changes (0). No changelog, support by email, not tested (5). In the official MCP registry as com.mermaidchart/mermaid-mcp, but the entry dates from 18 September 2025 and still points at mcp.mermaidchart.com rather than mcp.mermaid.ai (12). The SDK repo runs lint and tests in CI (6).

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.

Mermaid Chart MCP 34

25 tools on the live server per the 30 September check, 9 of them documented (15). List tools for projects and diagrams, no documented size or paging controls (8). Errors undocumented (3). No annotations or retry guidance found, live annotations unchecked (0). Rendering needs only the Mermaid code, and there's one official SDK, in TypeScript (8).

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.

Mermaid Chart MCP 20

Render and validation tools need no credentials. Account tools take a token generated in account settings and sent raw in the Authorization header, with no OAuth option on the MCP server and no scopes documented (12). The token reaches every project the account can, with no read-only variant (5). Project diagrams and the GitHub, Jira and Notion helpers can bring other people's text into context, and we found no injection guidance (3). No audit log found (0). No security page, disclosure policy or certification found, and /.well-known/security.txt answered 401 on 30 September (0).

AI Diagram Maker MCP 20

No x402, MPP or L402 (0). Plan prices are public (Plus $10, Max $20 a month), with credits counted at 1,000 tokens each, so there's no per-diagram price (10 of 20). Basic is free forever with 50 credits a month, but the page doesn't say whether a card is needed or whether API and MCP calls are included (10 of 20, half as with an unstated card rule). A person signs up in the app and creates the key (0). 0 + 10 + 10 + 0 = 20.

Mermaid Chart MCP 45

No x402, MPP or L402 (0). Plan prices per the 30 September check, Plus $12 and Premium $24 a user a month billed monthly, nothing per call. The pricing page needs JavaScript and didn't render for us today (10). Rendering and validation are free with no account (20). An agent can render and validate without any signup, but saving to projects needs a person to create an account and token (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.

Mermaid Chart MCP 15

No status page. The docs link none, and status.mermaidchart.com fails its TLS handshake (0). No readable incident history (5). No rate limits documented (0). No 429 or retry guidance (0). The terms promise "commercially reasonable efforts" and no SLA (0). The server is listed in the official registry as 1.0.0 and documented as a product, not a beta (10).