browser-firefox-mcp

by ironessi

Overview Schema Source Related Servers Discussions Admin

Python

Local

inject_payload

Inject a custom payload into a selected element and verify reflection to test for injection vulnerabilities.

Instructions

Inject a single custom payload into a target element and verify reflection.

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": {
      "selector": "<selector>",
      "payload": "<payload>"
    },
    "name": "inject_payload"
  }
}

Input Schema

Name	Required	Description	Default
`payload`	Yes
`selector`	Yes

Schema Changelog

Changes observed during successful MCP inspections.

First observedv0.1.0Aug 20, 2026

TDQS

C2.7/5.0

Behavior2/5

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

The description says it injects and verifies reflection, but with no annotations it must also disclose side effects, whether the payload executes, whether it modifies the page/DOM, what 'verify reflection' entails, and any potential impact. None of that is covered.

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

Conciseness4/5

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

The description is compact and front-loaded, delivering the core action in one sentence. However, it is slightly too sparse given the need for behavioral and parameter context.

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?

This is a potentially impactful injection tool with two arbitrary string parameters, no annotations, and no output schema. The description does not mention return values, success/failure conditions, page impact, relation to XSS injection, or guidance on payload construction, leaving significant gaps for the agent.

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

Parameters2/5

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

Schema description coverage is 0%, so the description must compensate. It loosely hints that 'selector' selects the target element and 'payload' is the custom input, but it does not explain the expected format, whether selector is CSS/XPath, what values payload should take, or how reflection is verified.

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 clearly states the action ('inject') and target ('target element') plus the follow-up verification ('verify reflection'). It distinguishes itself somewhat from sibling tools by emphasizing custom payload and verification, though it does not explicitly contrast with inject_xss_payload.

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?

No guidance is provided about when to use this tool versus alternatives such as inject_xss_payload, find_reflection, or fill_input. The context implies injection testing, but there are no explicit conditions, prerequisites, or exclusions.

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