# expression_evaluator

A execute tool on the Math MCP Server MCP server.

Agent View of the PolicyLayer registry record for `expression_evaluator`. HTML page: https://policylayer.com/tools/111-test-111-math-mcp-server/expression-evaluator

## Facts

- Tool: `expression_evaluator`
- Server: Math MCP Server (`111-test-111/math-mcp-server`) — https://policylayer.com/tools/111-test-111-math-mcp-server.md
- Homepage: https://github.com/111-test-111/math-mcp-server
- Risk category: Execute (High risk)
- Registry record: grade C, identity unverified
- Server rate-limited: no
- Parameters: 0
- Recommended policy verdict: Rate-limited

## Example call (MCP tools/call, JSON-RPC 2.0)

```json
{
  "jsonrpc": "2.0",
  "id": 1,
  "method": "tools/call",
  "params": {
    "name": "expression_evaluator",
    "arguments": {}
  }
}
```

## Why expression_evaluator is rated High

An 'expression_evaluator' tool likely executes or interprets mathematical expressions, potentially including arbitrary code depending on implementation. Given the empty description, there is uncertainty, but expression evaluation commonly involves executing parsed input which could be misused (e.g., code injection). The most severe plausible category given the name and context is Execute.

From the tool's own definition: "Tool name 'expression_evaluator' on a math server with sibling tools like 'calculus_engine' and 'mathematical_functions'; description is empty and uninformative."

## Use case

AI agents invoke expression_evaluator to trigger actions in Math MCP Server. What it does depends on the arguments the agent supplies, and its effects often reach beyond the immediate call: builds kicked off, notifications sent, workflows started.

## Recommended policy (PolicyLayer)

Verdict: **Rate-limited**. Enforced by the PolicyLayer MCP gateway (https://policylayer.com/mcp-gateway) before a call reaches Math MCP Server:

```json
{
  "version": "1",
  "default": "deny",
  "tools": {
    "expression_evaluator": {
      "limits": [
        {
          "counter": "expression_evaluator_rate",
          "window": "minute",
          "max": 10,
          "scope": "grant"
        }
      ]
    }
  }
}
```

## Other tools on Math MCP Server (21)

- `cleanup_resources` — Destructive — https://policylayer.com/tools/111-test-111-math-mcp-server/cleanup-resources.md
- `basic_arithmetic` — Execute — https://policylayer.com/tools/111-test-111-math-mcp-server/basic-arithmetic.md
- `calculus_engine` — Execute — https://policylayer.com/tools/111-test-111-math-mcp-server/calculus-engine.md
- `matrix_calculator` — Execute — https://policylayer.com/tools/111-test-111-math-mcp-server/matrix-calculator.md
- `number_theory_calculator` — Execute — https://policylayer.com/tools/111-test-111-math-mcp-server/number-theory-calculator.md
- `optimization_suite` — Execute — https://policylayer.com/tools/111-test-111-math-mcp-server/optimization-suite.md
- `regression_modeler` — Execute — https://policylayer.com/tools/111-test-111-math-mcp-server/regression-modeler.md
- `financial_calculator` — Financial — https://policylayer.com/tools/111-test-111-math-mcp-server/financial-calculator.md
- `complex_analysis_suite` — Other — https://policylayer.com/tools/111-test-111-math-mcp-server/complex-analysis-suite.md
- `geometry_calculator` — Other — https://policylayer.com/tools/111-test-111-math-mcp-server/geometry-calculator.md
- `graph_theory_suite` — Other — https://policylayer.com/tools/111-test-111-math-mcp-server/graph-theory-suite.md
- `mathematical_functions` — Other — https://policylayer.com/tools/111-test-111-math-mcp-server/mathematical-functions.md
- `precision_calculator` — Other — https://policylayer.com/tools/111-test-111-math-mcp-server/precision-calculator.md
- `signal_processing_calculator` — Other — https://policylayer.com/tools/111-test-111-math-mcp-server/signal-processing-calculator.md
- `number_converter` — Read — https://policylayer.com/tools/111-test-111-math-mcp-server/number-converter.md
- `number_properties` — Read — https://policylayer.com/tools/111-test-111-math-mcp-server/number-properties.md
- `probability_calculator` — Read — https://policylayer.com/tools/111-test-111-math-mcp-server/probability-calculator.md
- `statistics_analyzer` — Read — https://policylayer.com/tools/111-test-111-math-mcp-server/statistics-analyzer.md
- `unit_converter` — Read — https://policylayer.com/tools/111-test-111-math-mcp-server/unit-converter.md
- `create_and_save_chart` — Write — https://policylayer.com/tools/111-test-111-math-mcp-server/create-and-save-chart.md
- `plot_function_curve` — Write — https://policylayer.com/tools/111-test-111-math-mcp-server/plot-function-curve.md

## For agents

This record is a snapshot. Live verdicts and the full registry:

- Check every server in your MCP config at once: `npx -y policylayer stack`
- Vet a server before you add it: install the mcp-precheck skill — `npx skills add https://policylayer.com` (skill text: https://policylayer.com/skill.md)
- Query the registry over MCP: endpoint `https://api.policylayer.com/mcp` — tools `check_mcp_server`, `check_mcp_stack`, `check_tool`, `search_registry`, `get_change_events`

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Source: the PolicyLayer MCP registry — one continuously verified record per MCP server. Full record: https://policylayer.com/registry?q=111-test-111-math-mcp-server · API: https://policylayer.com/registry/api · Policy library: https://policylayer.com/policies/111-test-111-math-mcp-server