write_jsxn

// WHEN AI AGENTS USE THIS TOOL

AI agents use write_jsxn to create or modify resources in Jsx Notation. Write operations carry medium risk because an autonomous agent could trigger bulk unintended modifications. Rate limits prevent a single agent session from making hundreds of changes in rapid succession. Argument validation ensures the agent passes expected values.

// WHY ENFORCE A POLICY ON WRITE_JSXN

Without a policy, an AI agent could call write_jsxn repeatedly, creating or modifying resources faster than any human could review. Intercept's rate limiting ensures write operations happen at a controlled pace, and argument validation catches malformed or unexpected inputs before they reach Jsx Notation.

// RECOMMENDED POLICY

Write tools can modify data. A rate limit prevents runaway bulk operations from AI agents.

io-github-sebastianmaciel-jsx-notation.yaml

tools:
  write_jsxn:
    rules:
      - action: allow
        rate_limit:
          max: 30
          window: 60

See the full Jsx Notation policy for all 4 tools.

// DETAILS

Tool Name write_jsxn

Category Write

MCP Server Jsx Notation MCP Server

Risk Level Medium

// MORE JSX NOTATION TOOLS

Read decode_jsxn Read encode_jsxn Read read_jsxn

// WHAT CAN GO WRONG

Agents calling write-class tools like write_jsxn have been implicated in these attack patterns. Read the full case and prevention policy for each:

Browse the full MCP Attack Database →

// OTHER WRITE TOOLS ACROSS MCP SERVERS

Other tools in the Write risk category across the catalogue. The same policy patterns (rate-limit, validate) apply to each.

AbraFlexi contact_create AbraFlexi contact_update AbraFlexi evidence_create AbraFlexi evidence_update AbraFlexi invoice_issued_update AbraFlexi invoice_received_create

// RELATED READING

// FAQ

What does the write_jsxn tool do? +

Decodes JSXN notation and writes the resulting JSX/TSX or HTML to a file on disk. Creates parent directories if needed. Writes to .jsx/.tsx/.js/.ts/.html/.svg files. For .html and .svg files, decodes with HTML format (class attrs, void elements, SVG self-closing, etc.). ## JSXN Format Reference JSXN is a compact notation for React/Next.js code that saves ~40% tokens. ### File-level headers - `@I module: default Name, x, y` → `import Name, { x, y } from "module"` - `@I "styles.css"` → `import "styles.css"` - `@T module: Type1` → `import type { Type1 } from "module"` ### Directives - `"use client"` / `"use server"` → passed through as-is ### Types - `Name { field: Type }` → `interface Name { field: Type }` - `Name = Type | Other` → `type Name = Type | Other` ### Function blocks - `export default Name(params)` → function signature - `@state count = 0` → `const [count, setCount] = useState(0)` - `@ref inputRef = null` → `const inputRef = useRef(null)` - `name = useHook(args)` → `const name = useHook(args)` - `variable = expr` → `const variable = expr` - `let variable = expr` → preserved as `let` - `---` → separator; everything after is the JSX return body ### JSX body notation - **Alias headers** (optional): `@C Button=B`, `@P onClick=k`, `@S items-center=ic` - **Elements**: `tag.class1.class2#id {prop:val, flag} "text"` or `(expr)` - **Implicit div**: `.className` (div is omitted when it has selectors) - **Nesting**: 1-space indentation per level - **Fragments**: `_` → `<>...</>` - **Conditionals**: `?cond > Element` → `{cond && (<Element />)}` - **Ternaries**: `?cond > A | B` → `{cond ? (<A />) : (<B />)}` - **Maps**: `*items > Element` → `{items.map(item => (<Element />))}` - **Text nodes**: `"Hello"` → raw text - **Expressions**: `(expr)` → `{expr}` - **Props**: `{key:value}` string for HTML attrs, `{key:expr}` expression otherwise - **Boolean props**: `{disabled}` → `disabled` - **Spread**: `{...props}` → `{...props}` - **Self-closing**: element with no children → `<Element />` - **Member expressions**: `Form.Input` (dot after uppercase = member, not class) ### Example ``` @C Modal=M, Button=B @P onClick=k, disabled=x M {isOpen:show, onClose:handleClose} .modal-body h2 (title) ?error > Alert {type:error} (error) ul.item-list *items > li.item {key:item.id, k:()=>select(item)} (item.name) B {x:!selected, k:handleSubmit} "Confirm" ```. It is categorised as a Write tool in the Jsx Notation MCP Server, which means it can create or modify data. Consider rate limits to prevent runaway writes.

How do I enforce a policy on write_jsxn? +

Add a rule in your Intercept YAML policy under the tools section for write_jsxn. You can allow, deny, rate-limit, or validate arguments. Then run Intercept as a proxy in front of the Jsx Notation MCP server.

What risk level is write_jsxn? +

write_jsxn is a Write tool with medium risk. Write tools should be rate-limited to prevent accidental bulk modifications.

Can I rate-limit write_jsxn? +

Yes. Add a rate_limit block to the write_jsxn rule in your Intercept policy. For example, setting max: 10 and window: 60 limits the tool to 10 calls per minute. Rate limits are tracked per agent session and reset automatically.

How do I block write_jsxn completely? +

Set action: deny in the Intercept policy for write_jsxn. The AI agent will receive a policy violation error and cannot call the tool. You can also include a reason field to explain why the tool is blocked.

What MCP server provides write_jsxn? +

write_jsxn is provided by the Jsx Notation MCP server (jsx-notation). Intercept sits as a proxy in front of this server to enforce policies before tool calls reach the server.

Enforce policies on Jsx Notation