This record as markdown: /tools/io-tinyfn-tinyfn/hmac-sha512.md
What hmac_sha512 does on TinyFn
AI agents call hmac_sha512 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 |
|---|---|---|---|
key | string | Yes | Secret key |
message | string | Yes | Message to authenticate |
Parameters from the server's own tool schema.
Why hmac_sha512 is rated Low
HMAC-SHA512 is a deterministic cryptographic function that produces a hash output based on input data and a key. It retrieves/generates a computed value without creating, modifying, deleting, executing code, or moving money. While cryptographic operations could theoretically be misused in attack scenarios, the tool itself is a pure computation function with no inherent destructive or system-altering capabilities.
From the tool's definition Tool generates HMAC-SHA512 cryptographic hashes. The description indicates it computes and returns a hash value with no side effects on external state or data modification.
Attacks that exploit this kind of access
The rule that runs hmac_sha512 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 hmac_sha512, this is the rule to start with:
hmac_sha512 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 hmac_sha512 call is checked against it from then on.
Questions about hmac_sha512
Generate HMAC-SHA512. It is categorised as a Read tool in the TinyFn MCP Server, which means it retrieves data without modifying state.
hmac_sha512 accepts 2 parameters: key, message. Required: key, message. 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 hmac_sha512: 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.
hmac_sha512 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 hmac_sha512 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 hmac_sha512. 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.
hmac_sha512 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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