gribstream_get_expression_reference

SERVERGribStream MCP SOURCEhttps://gribstream.com/mcp

Low RISK CLASS

Category Read

Parameters 00 required

Recommended Allowedsee the rule below

Registry record Grade F, identity unverified Pull the record →

This record as markdown: /tools/com-gribstream-mcp/gribstream-get-expression-reference.md

WHAT IT DOES

What gribstream_get_expression_reference does on GribStream MCP

AI agents call gribstream_get_expression_reference to retrieve information from GribStream MCP without modifying anything. It is typically the context-gathering step in research, monitoring, and reporting workflows, before the agent takes action elsewhere.

RISK

Why gribstream_get_expression_reference is rated Low

This tool retrieves static reference documentation (expression language syntax, function list, examples) with no side effects, no data modification, and no ability to access or return actual weather data. It is a pure read operation returning informational content.

From the tool's definition Tool description explicitly states 'NO AUTH / PUBLIC / READ-ONLY' and 'Gets the GribStream expression language reference'. It 'does not query weather values and cannot return forecast data', confirming it only retrieves reference documentation.

Attacks that exploit this kind of access

RECOMMENDED RULE

The rule that runs gribstream_get_expression_reference safely

PolicyLayer is an MCP gateway: it sits between your AI agents and GribStream MCP, and checks every tool call against a rule you set before the call runs. Nothing changes on the server itself. For gribstream_get_expression_reference, this is the rule to start with:

gribstream_get_expression_reference Allowed

gribstream_get_expression_reference is read-only, so it stays allowed. Everything else on the server is denied unless you say otherwise.

View as policy code

policy.json

{
  "version": "1",
  "default": "deny",
  "tools": {
    "gribstream_get_expression_reference": {}
  }
}

ALLOW ONLY THIS TOOL → Instant setup, no code required.

The button opens the PolicyLayer dashboard: create your workspace, connect GribStream MCP, apply this rule, and every gribstream_get_expression_reference call is checked against it from then on.

FAQ

Questions about gribstream_get_expression_reference

What does the gribstream_get_expression_reference tool do? +

NO AUTH / PUBLIC / READ-ONLY. Gets the GribStream expression language reference, including github.com/expr-lang/expr syntax guidance, alias rules, examples, and the full exported func.* math function list. This tool does not query weather values and cannot return forecast data. It is categorised as a Read tool in the GribStream MCP MCP Server, which means it retrieves data without modifying state.

How do I enforce a policy on gribstream_get_expression_reference? +

Register the GribStream MCP server in PolicyLayer and add a rule for gribstream_get_expression_reference: 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 GribStream MCP. Nothing to install.

What risk level is gribstream_get_expression_reference? +

gribstream_get_expression_reference is a Read tool with low risk. Read-only tools are generally safe to allow by default.

Can I rate-limit gribstream_get_expression_reference? +

Yes. Add a rate_limit block to the gribstream_get_expression_reference 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.

How do I block gribstream_get_expression_reference completely? +

Set action: deny in the PolicyLayer policy for gribstream_get_expression_reference. 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 gribstream_get_expression_reference? +

gribstream_get_expression_reference is provided by the GribStream MCP server (https://gribstream.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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