Skip to main content
Glama
Sign In
agent-browser

agent-browser

by EgiStr
OverviewSchemaSourceRelated ServersDiscussionsAdmin
Python
Hybrid

evaluate

Execute custom JavaScript in the agent tab to extract data or interact with pages, returning results as JSON for further processing.

Instructions

Run a JavaScript expression or function in the agent tab; returns the result as JSON.

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": {
      "script": "<script>"
    },
    "name": "evaluate"
  }
}

Input Schema

NameRequiredDescriptionDefault
scriptYes

Output Schema

NameRequiredDescriptionDefault
resultYes

Schema Changelog

Changes observed during successful MCP inspections.

  1. First observedv0.2.0

TDQS

C2.9/5.0
Behavior2/5

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

No annotations are provided, so the description carries the full behavioral burden. It says the return is JSON, but it does not disclose permissions, sandboxing, side effects, async handling, error behavior, or risks of arbitrary code execution.

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?

A single front-loaded sentence with no wasted words. The verb and resource appear immediately, and the return note is compact.

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

Completeness2/5

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

An output schema exists, so return values need not be explained. However, for an arbitrary-code-execution tool with no annotations and an undocumented parameter, the description omits critical context such as permissions, execution limits, error behavior, and side effects.

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?

The single parameter has 0% schema description coverage, so the description must compensate. It does clarify that "script" accepts a JavaScript expression or function, adding meaningful semantics beyond the bare schema, but it gives no examples, async behavior, or expected return handling.

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

Purpose4/5

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

The description states a specific verb ("Run") and resource ("a JavaScript expression or function in the agent tab"), so the agent can tell it executes code rather than manipulating the browser UI. It does not explicitly distinguish itself from siblings, but its purpose is clear enough to stand alone.

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

Usage Guidelines2/5

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

It mentions the execution context ("agent tab") but gives no guidance on when to use this tool instead of siblings such as navigate, click, or page_snapshot. There are no exclusions or alternative-selection cues.

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

Deploy Server

Other Tools