Getting it into your agent
One page per mod, every tool's command on it. A separate URL per tool would split the same page into five that compete with each other.
npx agentmods add rules/peternagy1332/json-editor-mcp/json-editor-mcpgit clone --depth 1 https://github.com/peternagy1332/json-editor-mcpWrote 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.
[](https://agentmods.dev/rules/peternagy1332/json-editor-mcp/json-editor-mcp)<a href="https://agentmods.dev/rules/peternagy1332/json-editor-mcp/json-editor-mcp"><img src="https://agentmods.dev/badge/rules/peternagy1332/json-editor-mcp/json-editor-mcp.svg" alt="Measured on agentmods" height="20"></a>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 | $0.00000 | $0.00532 |
| Opus 5 | $0.00000 | $0.00266 |
| Sonnet 5 | $0.00000 | $0.00106 |
| Haiku 4.5 | $0.00000 | $0.00053 |
Grade A, and why
json-editor-mcp 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 5d 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.
How it starts
The opening of the file, as written. The whole thing — 69 lines — stays where its author put it; the contents beside it link to each section on GitHub.
JSON File Editing with MCP Tools
When editing JSON files (especially translation files like messages/*.json, i18n files, or any JSON configuration), ALWAYS use the JSON Editor MCP tools instead of directly editing the files:
Available Tools:
read_json_value- Read values from JSON files using dot notation pathswrite_json_value- Write values to JSON files with automatic path creationmerge_duplicate_keys- Deep merge duplicate keys in JSON files
Usage Guidelines:
For Reading JSON Values:
- Use
read_json_valueto read specific values from JSON files - Example:
read_json_value("messages/en.json", "common.welcome") - Always specify the full file path and dot notation path
For Writing JSON Values:
- Use
write_json_valueto add or update values in JSON files - Example:
write_json_value("messages/en.json", "common.greeting", "Hello World") - The tool automatically creates missing paths
- Supports nested objects:
write_json_value("config.json", "database.host", "localhost")
For Merging Duplicate Keys:
- Use
merge_duplicate_keyswhen JSON files have duplicate keys - Example:
merge_duplicate_keys("messages/en.json") - This performs deep merge with last value wins for primitives
When to Use These Tools:
- ✅ Editing translation files (messages/*.json)
- ✅ Updating configuration files
- ✅ Managing i18n/locale files
- ✅ Any JSON file manipulation
- ❌ Don't use for non-JSON files
- ❌ Don't manually edit JSON files when these tools are available
Examples for Common Scenarios:
Adding a new translation:
write_json_value("messages/en.json", "pages.about.title", "About Us")
Reading existing translation:
read_json_value("messages/es.json", "common.welcome")
Updating nested configuration:
write_json_value("config.json", "api.endpoints.users", "/api/v1/users")
Merging duplicate keys after manual editing:
merge_duplicate_keys("messages/en.json")
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.
- 5d ago First seen · 69 lines · 532 tokens per session scan A bad3e250df5c
json-editor-mcp is a cursor rule published in the GitHub repository peternagy1332/json-editor-mcp (1 stars, last pushed 10mo ago), licensed MIT. It costs nothing until one of its globs matches a file; then it loads 532 tokens. 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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