web-ui-tester

Console log

browser_console

Retrieve buffered console messages and uncaught page errors with stack traces to diagnose why a page misbehaves. Filter by severity or read since last call.

Instructions

Returns buffered console messages and uncaught page errors (with stacks). Check this whenever the page misbehaves — it usually names the failure directly.

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": {
      "sessionId": "<sessionId>"
    },
    "name": "browser_console"
  }
}

Input Schema

Name	Required	Description
`clear`	No	Empty the buffer after reading.
`level`	No	Filter by level. "error" also includes uncaught page errors.
`limit`	No	Max entries (default 50).
`sessionId`	Yes	Session id returned by browser_start.
`sinceLastCall`	No	Only entries since the previous call (default true).

Schema Changelog

Changes observed during successful MCP inspections.

First observedv0.1.0Aug 24, 2026

TDQS

A4.2/5.0

Behavior4/5

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

Annotations are minimal (readOnlyHint=false, openWorldHint=true), so the description adds meaningful behavioral context: it returns buffered console messages plus uncaught page errors with stacks, and it often directly names the failure. The clear parameter's destructive behavior is documented in the schema rather than the description, which is acceptable since annotations already signal possible mutation.

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 tightly written sentences: the first states the result and content, the second gives practical usage guidance. No wasted words, and the most important information is front-loaded.

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?

The description combined with the rich input schema and annotations is largely sufficient for an agent to select and call the tool. It lacks an explicit output format, but with no output schema present, the mention of 'messages' and 'errors (with stacks)' gives enough shape for first use. Parameter defaults and clearing behavior are covered by the schema.

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

Parameters3/5

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

Schema description coverage is 100%, so all five parameters already have clear descriptions and constraints. The tool description adds little parameter-level meaning beyond the schema, but it does reinforce that 'error' level includes uncaught page errors, which aligns with the schema's filter description.

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 names a specific verb and resource: 'Returns buffered console messages and uncaught page errors (with stacks).' It clearly differentiates from sibling browser tools like browser_network, browser_snapshot, and browser_request_detail by focusing on console output and page errors.

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?

The description gives explicit when-to-use guidance: 'Check this whenever the page misbehaves.' It doesn't explicitly name alternatives or when-not-to-use cases, so it falls just short of a 5, but the usage context is clear and actionable.

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