JsonMend

dev.workers.mike-tusa.jsonmendPublished by jsonmend.mike-tusa.workers.devOfficial publisherv0.1.3Updated Oct 25, 2026

Repair broken JSON from LLM output and validate it against a JSON Schema.

VerifiedStreamable HTTPWeb executableDeveloper Tools

Overview

AI-generated overview

A remote MCP server that repairs malformed JSON and validates JSON against a JSON Schema, returning errors with JSON Pointer paths.

What you can do
Repair broken or messy JSON text into valid JSON, stripping code fences, prose, comments and trailing commas and closing truncated structures. Validate JSON against a JSON Schema and get every error with its JSON Pointer path. Accept JSON as raw text (repaired first, with fixes listed) or as an already-parsed value. Optionally coerce values such as strings to numbers or booleans toward the schema's types.
When to use it
Useful when an assistant handles JSON produced by LLMs or other unreliable sources and needs to clean it up or check it against a schema before using it. Also handy for diagnosing schema validation errors with precise paths.
Requirements
A remote endpoint reached over streamable HTTP; no local runtime or package is needed. No account is required, but an optional Authorization header with a Bearer key (a free key) raises rate limits.
Before you install
The optional Authorization header carries a secret key; only send it if you are comfortable sharing it with the remote service. JSON content submitted for repair or validation is sent to a third-party server, so avoid sending sensitive data.

Installation

In SourceWeft

  1. Open JsonMend in the dashboard and add it to a workspace.
  2. Enable the server for the chats that should use its tools.

Web executable via Streamable HTTP. Remote servers run from the web runtime once configured in a workspace.

Use with an agent

Paste this prompt into Claude Code, Codex, Cursor or another agent — or into SourceWeft chat. The agent reads this server's install guide, shows you its publisher, endpoint and sign-in, and adds it to your client once you agree. Keys never go into a command.

Read https://sourceweft.com/mcp/dev.workers.mike-tusa.jsonmend%2Fjsonmend/install.md and connect the MCP server it describes to my client. Before changing any config, show me its publisher, endpoint and sign-in method and wait for my OK. Never put an API key in a command or in a file I would commit; ask me where it should come from.

Read the install guide the agent follows

Other MCP clients

Add this to your client's mcpServers config.

{
  "mcpServers": {
    "jsonmend": {
      "type": "http",
      "url": "https://jsonmend.mike-tusa.workers.dev/mcp"
    }
  }
}

Tools

2

repair_json

Repair broken JSON (LLM output) and list the fixes

Turn broken or messy JSON text into valid JSON. Strips Markdown code fences and prose before/after the JSON, removes comments and trailing commas, converts single/curly quotes, quotes unquoted keys, maps Python None/True/False, inserts missing commas, closes truncated strings/arrays/objects, and wraps NDJSON / several concatenated objects into one array. Returns the parsed value (json), the repaired text, and the list of fixes applied; valid input passes through unchanged with no fixes. Optional schema (+ coerce) also validates the result. Fails with isError (code unrepairable / no_json_found) when nothing JSON-like can be recovered. Pure computation: read-only, no network access, inputs not stored. Same engine and limits as POST /api/v1/repair.

Parametersdraftinputrequiredcoerceformatschema

validate_json

Validate JSON against a JSON Schema (repairs broken input first)

Check JSON against a JSON Schema and get every error with its JSON Pointer path. Send the JSON either as text ("input"; broken text is repaired first, and the fixes are listed) or as an already-parsed value ("data"). Optional coerce converts "42" → 42, "true" → true, etc. toward the schema's types before validating and lists each change. A schema mismatch is a normal result (valid: false), not an error. Drafts 2020-12 (default), 2019-09, 7, 4; only local $refs. Pure computation: read-only, no network access, inputs not stored. Same engine and limits as POST /api/v1/validate.

Parametersdatadraftinputcoerceschemarequired

Version history

1
  1. v0.1.3LatestOct 15, 2026

Score

83% of the applicable checks met

How complete this listing is, computed from the registry entry, the endpoint and public sources. Not a rating of the server and not a statement that it is safe or working today: reachability is a dated check, and no installs or reviews go into the score.

  • Reached in the last 30 daysRequired25 pts
  • Auth declaredRequired10 pts
  • Tools listedRequired15 pts
  • DescriptionRequired15 pts
  • Logo10 pts
  • Documentation15 pts

    Declare a GitHub repository with a README, or serve resource_documentation in the OAuth protected-resource metadata.

  • LicenseNot applicable

    A hosted service is used under its provider's terms, so no license is expected here. This check is left out of the percentage.