shinyprobe

get_errors

Retrieve detailed Shiny app errors, including server traces, output failures, browser console errors, and app exits. Set since_last to get only errors since the previous check.

Instructions

Every error seen so far: server errors with traces (and the output they broke), Shiny output errors, browser console errors, and the app exiting. With since_last=True, only errors since the previous since_last call.

Tool call template

Replace each placeholder with a value matching the input schema. Only required parameters are included; add optional parameters as needed.

{
  "id": 1,
  "jsonrpc": "2.0",
  "method": "tools/call",
  "params": {
    "arguments": {
      "app_id": "<app_id>"
    },
    "name": "get_errors"
  }
}

Input Schema

Name	Required	Description	Default
`app_id`	Yes
`since_last`	No

Schema Changelog

Changes observed during successful MCP inspections.

First observedv0.1.0Sep 25, 2026

TDQS

A4.4/5.0

Behavior4/5

Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?

With no annotations, the description carries the behavioral burden well. It reveals that errors accumulate, that server errors include traces and the output they broke, and that since_last defines a query window relative to the previous since_last call. It does not mention response format or side effects, but nothing contradicts the tool behavior.

Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.

Conciseness5/5

Is the description appropriately sized, front-loaded, and free of redundancy?

Two dense sentences with no filler. The first sentence front-loads the tool's scope with specific error categories, and the second handles the main parameter behavior. Every sentence earns its place.

Shorter descriptions cost fewer tokens and are easier for agents to parse. Every sentence should earn its place.

Completeness4/5

Given the tool's complexity, does the description cover enough for an agent to succeed on first attempt?

For a two-parameter read tool with no output schema, the description sufficiently explains what the agent will receive and how since_last changes the result. It could be more explicit about return shape or that app_id scopes the errors, but the core contract is clear.

Complex tools with many parameters or behaviors need more documentation. Simple tools need less. This dimension scales expectations accordingly.

Parameters4/5

Does the description clarify parameter syntax, constraints, interactions, or defaults beyond what the schema provides?

Schema description coverage is 0%, but the description adds meaningful semantics for since_last: 'only errors since the previous since_last call.' app_id is not elaborated, though its role is reasonably clear from the parameter name and app-centric sibling tools.

Input schemas describe structure but not intent. Descriptions should explain non-obvious parameter relationships and valid value ranges.

Purpose5/5

Does the description clearly state what the tool does and how it differs from similar tools?

The description identifies the resource (errors) and enumerates concrete error categories: server errors with traces, Shiny output errors, browser console errors, and app exits. This clearly distinguishes get_errors from siblings like get_console and read_outputs.

Agents choose between tools based on descriptions. A clear purpose with a specific verb and resource helps agents select the right tool.

Usage Guidelines4/5

Does the description explain when to use this tool, when not to, or what alternatives exist?

It provides clear context: this is the comprehensive error-listing tool, and explains when to use since_last=True. It does not explicitly name alternatives or state when not to use it, so it stops short of a 5.

Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.

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