This record as markdown: /tools/io-tinyfn-tinyfn/flatten-json.md
What flatten_json does on TinyFn
AI agents call flatten_json to retrieve information from TinyFn without modifying anything. It is typically the context-gathering step in research, monitoring, and reporting workflows, before the agent takes action elsewhere.
| Parameter | Type | Required | Description |
|---|---|---|---|
separator | string | — | Key separator |
json_string | string | Yes | JSON string to flatten |
Parameters from the server's own tool schema.
Why flatten_json is rated Low
This tool takes a nested JSON object and flattens it into a single-level structure. It is a deterministic data transformation with no external side effects, no writes, no deletions, and no execution of code. It fits squarely in the Read category as it processes and returns data.
From the tool's definition Flatten a nested JSON object — purely transforms/reads input data with no side effects
Attacks that exploit this kind of access
The rule that runs flatten_json safely
PolicyLayer is an MCP gateway: it sits between your AI agents and TinyFn, and checks every tool call against a rule you set before the call runs. Nothing changes on the server itself. For flatten_json, this is the rule to start with:
flatten_json is read-only, so it stays allowed. Everything else on the server is denied unless you say otherwise.
The button opens the PolicyLayer dashboard: create your workspace, connect TinyFn, apply this rule, and every flatten_json call is checked against it from then on.
Questions about flatten_json
Flatten a nested JSON object. It is categorised as a Read tool in the TinyFn MCP Server, which means it retrieves data without modifying state.
flatten_json accepts 2 parameters: separator, json_string. Required: json_string. The full parameter table on this page comes from the server's own tool schema.
Register the TinyFn MCP server in PolicyLayer and add a rule for flatten_json: allow, deny, rate-limit, or require approval. Point your MCP client at the PolicyLayer proxy URL and the rule is enforced on every call, before it reaches TinyFn. Nothing to install.
flatten_json is a Read tool with low risk. Read-only tools are generally safe to allow by default.
Yes. Add a rate_limit block to the flatten_json rule in your PolicyLayer 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.
Set action: deny in the PolicyLayer policy for flatten_json. 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.
flatten_json is provided by the TinyFn MCP server (https://api.tinyfn.io/mcp/all/). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.
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