What is kroki-mcp CLAUDE.md?

A project instruction file for a Python server that sends diagram descriptions to Kroki, a service that turns text into diagrams. It documents the code layout, conventions, and important implementation patterns.

Use it when adding or changing diagram rendering, diagram-type validation, configuration, server tools, or related Python code in kroki-mcp.

It gives the coding agent the project rules and structure needed to make consistent changes without guessing. It also records which parts are read-only and should not be modified.

How pvliesdonk/kroki-mcp configures Claude Code

Reuse

Borrowing it

Nothing to install: this file belongs to pvliesdonk/kroki-mcp. Take a copy, put it at the same path in your own repository, and replace the rules that are about this project with yours.

Copy the file

curl -O https://raw.githubusercontent.com/pvliesdonk/kroki-mcp/main/CLAUDE.md

Clone the repo

git clone --depth 1 https://github.com/pvliesdonk/kroki-mcp

Made for: Claude Code.

Wrote this? Show the measurements

A badge with what this costs and how it scanned, read live from this page, so it follows the numbers instead of freezing them. Markdown for a README, HTML for a documentation site or a project page.

README.md

[![agentmods](https://agentmods.dev/badge/instructions/pvliesdonk/kroki-mcp/claude-md/github.svg)](https://agentmods.dev/instructions/pvliesdonk/kroki-mcp/claude-md)

Your own site

<a href="https://agentmods.dev/instructions/pvliesdonk/kroki-mcp/claude-md"><img src="https://agentmods.dev/badge/instructions/pvliesdonk/kroki-mcp/claude-md/github.svg" alt="Measured on agentmods" height="20"></a>

Or the 80×15 button, for a site that already has a row of RSS and ATOM ones. Only the verdict fits; the numbers stay here.

Your own site · 80×15

<a href="https://agentmods.dev/instructions/pvliesdonk/kroki-mcp/claude-md"><img src="https://agentmods.dev/badge/instructions/pvliesdonk/kroki-mcp/claude-md.svg" alt="Reviewed on agentmods" width="80" height="20"></a>

Per session 432 This file is loaded in full into every session.

When invoked 432 The same file — it is already loaded in full.

Security scan A 0 findings. A grade says what 26 rules found in the file — not that it is safe.

Origin original No closer match found in the catalogue.

Token cost

What it costs to keep this loaded

Counted locally with the o200k_base tokenizer, which is exact for GPT models; Claude uses its own tokenizer and its counts differ. Treat this as one consistent yardstick across the catalogue rather than a bill. Prices are per million input tokens.

Model	Per session	Once invoked
Fable 5.1	$0.00432	$0.00432
Opus 5.5	$0.00173	$0.00173
Sonnet 5.5	$0.00086	$0.00086
Haiku 4.5	$0.00043	$0.00043

Measured 2mo ago against content hash 46cc50afb234, method: parsed. Prices are Anthropic first-party input rates as of 2026-10-07, from the pricing page.

Security

Grade A, and why

kroki-mcp CLAUDE.md scanned grade A with 0 findings against 26 rules in 11 categories — prompt injection, anti-refusal, data exfiltration, privilege escalation, supply chain, agent snooping, system-prompt leakage, SSRF and excessive agency — measured 2mo ago.

A static scan of the body, not an audit. Every finding is printed with the line that produced it so you can judge whether it matters here. A mod is markdown that instructs an agent; that is exactly why what it instructs is worth reading.

Nothing flagged

None of the 26 patterns this scan looks for appear in this file: no shell pipes, no recursive deletes, no credential paths, no hidden text, no instruction-override or anti-refusal phrasing, no agent-config snooping. That is not a guarantee, it is the absence of the things that are checkable.

CLAUDE.md · 37 lines

What it actually says

kroki-mcp

MCP server wrapping a self-hosted Kroki instance for diagram rendering.

Project Structure

src/kroki_mcp/
  mcp_server.py        -- FastMCP server factory + auth wiring (don't modify)
  config.py            -- env var loading; KROKI_MCP_KROKI_URL + read_only
  cli.py               -- CLI entry point (serve command)
  _server_deps.py      -- lifespan: httpx.AsyncClient → Kroki
  _server_tools.py     -- render_diagram, list_diagram_types
  _server_resources.py -- kroki://health resource
  _server_prompts.py   -- diagram_helper prompt
  _diagram_types.py    -- static registry of Kroki diagram types

Conventions

Python 3.11+
uv for package management, ruff for linting/formatting (line length 88)
hatchling build backend
Conventional commits: feat:, fix:, docs:, refactor:, test:, chore:
Google-style docstrings on all public functions
logging.getLogger(__name__) throughout, no print()
Type hints everywhere

Key Patterns

Service object is httpx.AsyncClient with base_url pointed at Kroki
All tools are read-only — Kroki is a rendering service with no write operations
Diagram type validation uses static DIAGRAM_TYPES registry in _diagram_types.py
Auth: _build_bearer_auth() + _build_oidc_auth() called in create_server(); MultiAuth when both set
_ENV_PREFIX in config.py is KROKI_MCP — controls all env var names
FastMCP 3.x API: use server._lifespan_manager() (not test_client()) in tests; result.content[0] for tool results; result.contents[0].content for resource results

Changes

What this file has done since we first saw it

Hashed on every crawl. A supply-chain change to an agent config is a question of when, not whether, so the history is kept rather than the latest state alone.

2mo ago First seen · 37 lines · 432 tokens per session scan A 46cc50afb234

Subscribe to this mod's changes

kroki-mcp CLAUDE.md is an instructions file published in the GitHub repository pvliesdonk/kroki-mcp (0 stars, last pushed 4mo ago), licensed MIT. It adds 432 tokens to every session, about $0.0017 per session on Opus 5.5. A static security scan graded it A with 0 findings. No closer match exists in the catalogue, so it is treated as the original; first seen 2026-08-31.

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kroki-mcp: Instructions file for Claude Code