What is fireflyiii-mcp AGENTS.md?

Repository instructions for an MCP server that connects Claude Code or another MCP client to Firefly III, a personal-finance application.

Maintaining tools that query or manage Firefly III accounts, transactions, budgets, categories, bills, savings targets, and financial insights.

They explain the server's architecture, supported connection methods, configuration, and rules for handling financial operations consistently.

How daften/fireflyiii-mcp configures Codex and OpenCode

Reuse

Borrowing it

Nothing to install: this file belongs to daften/fireflyiii-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/daften/fireflyiii-mcp/main/AGENTS.md

Clone the repo

git clone --depth 1 https://github.com/daften/fireflyiii-mcp

Made for: Codex, OpenCode.

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/daften/fireflyiii-mcp/agents-md/github.svg)](https://agentmods.dev/instructions/daften/fireflyiii-mcp/agents-md)

Your own site

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

Per session 13,441 This file is loaded in full into every session.

When invoked 13,441 The same file — it is already loaded in full.

Security scan A 1 finding. 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	$0.13441	$0.13441
Opus 5.5	$0.05376	$0.05376
Sonnet 5.5	$0.02688	$0.02688
Haiku 4.5	$0.01344	$0.01344

Measured 8d ago against content hash 9eff5c3a7a87, method: parsed. Prices are Anthropic first-party input rates as of 2026-10-07, from the pricing page.

Security

Grade A, and why

fireflyiii-mcp AGENTS.md scanned grade A with 1 finding 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 8d 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.

Makes network callslowCapability

Not a fault in itself. Listed so you know the mod talks to something, and to what.

- **Always verify new or changed tool fields against the Firefly III OpenAPI spec before implementing.** Fetch the YAML with `curl -s "https://api-docs.firefly-iii.org/firefly-iii-6.5.5-v1.yaml" -A "Mozilla/5.0"` and gre

AGENTS.md · 635 lines

How it starts

The opening of the file, as written. The whole thing — 635 lines — stays where its author put it; the contents beside it link to each section on GitHub.

MCP server for Firefly III — Project Documentation

Project Overview

MCP server for Firefly III is a TypeScript implementation of an MCP (Model Context Protocol) server that bridges Claude Code to a running Firefly III personal finance instance. This is a greenfield, open-source project (MIT license).

Users can query their finances in natural language through Claude, getting answers about accounts, transactions, budgets, categories, bills, piggy banks, and financial insights without writing queries themselves.

Current state: 137 tools across 14 groups, full CRUD, stdio and HTTP (OAuth or PAT) transports, tool filtering via --preset/--groups/--read-only.

Architecture at a glance

MCP client (Claude Code / Desktop / ...)
        │
        │  stdio                          HTTP (StreamableHTTP, stateless)
        ▼                                 ▼
  StdioServerTransport          OAuth proxy (src/http.ts)
        │                         · /.well-known metadata, /oauth/{authorize,token,register,callback}
        │                           (404 instead, if FIREFLY_OAUTH_CLIENT_ID is unset — PAT-only mode)
        │                         · substitutes redirect_uri, Bearer guard
        │                         · per-request token via AsyncLocalStorage
        └────────────┬────────────┘
                     ▼
            McpServer (src/server.ts)
                     │  registerAllTools (src/tools/index.ts)
                     │  · TOOL_GROUPS / PRESETS filtering, read-only proxy
                     ▼
      Tool groups (src/tools/*.ts, 14 groups / 137 tools)
        · defineTool wrapper: zod validation, error formatting (src/tools/_helpers.ts)
        · autocomplete prompts with per-user TTL cache
                     │
                     ▼
        FireflyClient (src/client.ts)
        · Bearer auth, 30s timeout, FireflyError → friendly messages
                     │
                     ▼
        Transform layer (src/transform.ts)
        · unwraps JSON:API envelopes → flat objects + pagination
                     │
                     ▼
            Firefly III REST API (/api/v1)

Read the full file on GitHub · 635 lines

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.

8d ago Changed · +40 lines · +2,916 tokens per session 9eff5c3a7a87
23d ago Changed · +9 lines · +596 tokens per session 18b02f9de117
1mo ago Changed · +941 tokens per session da07b791c462
2mo ago Changed · +142 tokens per session f05730cbd419
2mo ago First seen · 586 lines · 8,846 tokens per session scan A a3dc773b02e5

Subscribe to this mod's changes

fireflyiii-mcp AGENTS.md is an instructions file published in the GitHub repository daften/fireflyiii-mcp (27 stars, last pushed today), licensed MIT. It adds 13,441 tokens to every session, about $0.0538 per session on Opus 5.5. A static security scan graded it A with 1 finding (makes network calls). No closer match exists in the catalogue, so it is treated as the original; first seen 2026-08-30.

Planning TypeScript Writing and docs firefly-iii mcp model-context-protocol personal-finance

fireflyiii-mcp AGENTS.md next to 6 instructions from other repositories
Mod	Type	Stars	Last push	Licence	Scan	Tokens	Works with
fireflyiii-mcp AGENTS.mddaften/fireflyiii-mcp	Instructions file	27	today	MIT	A	13,441	Codex, OpenCode
vscode buildNext.instructions.mdmicrosoft/vscode	Instructions file	195k	today	MIT	A	9,719	GitHub Copilot
next.js AGENTS.mdvercel/next.js	Instructions file	143k	today	MIT	A	7,461	Codex, OpenCode
vscode oss-third-party-notices.instructions.mdmicrosoft/vscode	Instructions file	195k	today	MIT	A	5,516	GitHub Copilot
langchain AGENTS.mdlangchain-ai/langchain	Instructions file	149k	today	MIT	A	4,680	Codex, OpenCode
vscode copilot-instructions.mdmicrosoft/vscode	Instructions file	195k	today	MIT	A	3,093	GitHub Copilot
deepseek-harness AGENTS.mddeepseek-ai/deepseek-harness	Instructions file	275k	3d ago	MIT	A	4,313	Codex, OpenCode

fireflyiii-mcp: Instructions file for Codex