json_pointer_extract
JSON Pointer (RFC 6901) Extractor — Resolve an RFC 6901 JSON Pointer against a JSON document and return the referenced value.
This record as markdown: /tools/com-wingmanprotocol-agent-gateway/json-pointer-extract.md
What json_pointer_extract does on Gateway
AI agents call json_pointer_extract to retrieve information from Gateway 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 |
|---|---|---|---|
pointer | string | Yes | RFC 6901 JSON Pointer string (e.g. '/foo/0'; '' means the whole document) |
document | object | array | string | number | boolean | null | Yes | JSON document to resolve the pointer against |
Parameters from the server's own tool schema.
Why json_pointer_extract is rated Low
This is a read-only JSON querying utility that resolves pointer paths and returns existing data without side effects. It matches the 'Read' category definition: retrieves or queries data with no side effects. The blast radius of misuse is minimal — an agent could only access data already present in the document, not modify, delete, or execute anything.
From the tool's definition Tool description explicitly states it 'Resolve[s] an RFC 6901 JSON Pointer against a JSON document and return[s] the referenced value' — a pure query/retrieval operation with no modification or execution capability.
Attacks that exploit this kind of access
The rule that runs json_pointer_extract safely
PolicyLayer is an MCP gateway: it sits between your AI agents and Gateway, and checks every tool call against a rule you set before the call runs. Nothing changes on the server itself. For json_pointer_extract, this is the rule to start with:
json_pointer_extract 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 Gateway, apply this rule, and every json_pointer_extract call is checked against it from then on.
Questions about json_pointer_extract
JSON Pointer (RFC 6901) Extractor — Resolve an RFC 6901 JSON Pointer against a JSON document and return the referenced value. It is categorised as a Read tool in the Gateway MCP Server, which means it retrieves data without modifying state.
json_pointer_extract accepts 2 parameters: pointer, document. Required: pointer, document. The full parameter table on this page comes from the server's own tool schema.
Register the Gateway MCP server in PolicyLayer and add a rule for json_pointer_extract: 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 Gateway. Nothing to install.
json_pointer_extract 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 json_pointer_extract 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 json_pointer_extract. 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.
json_pointer_extract is provided by the Gateway MCP server (https://wingmanprotocol.com/mcp). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.
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