SeleniumMCP

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add_cookie

Add a cookie dictionary to the current domain's cookie store, enabling session management and state persistence in automated browser tests.

Instructions

Add a Selenium cookie dict to the current domain.

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": {
      "cookie": "<cookie>"
    },
    "name": "add_cookie"
  }
}

Input Schema

Name	Required	Description	Default
`cookie`	Yes

Output Schema

Name	Required	Description	Default
No arguments

Schema Changelog

Changes observed during successful MCP inspections.

First observedv0.1.0Apr 26, 2026

TDQS

B3.2/5.0

Behavior2/5

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

No annotations are provided, so the description must reveal behavioral traits. It only states what the tool does but omits details such as whether it overwrites existing cookies, error handling for invalid domains, or response behavior. This is insufficient for a mutation operation.

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 a single sentence, efficient and to the point. However, it could be slightly expanded to include key details without losing conciseness.

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?

Given the tool's simplicity (one parameter) and presence of sibling cookie tools, the description should at least hint at the cookie dict format or behavior on duplicates. It falls short of providing a complete picture for safe usage.

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?

The input schema has one parameter 'cookie' with 0% description coverage. The description calls it a 'Selenium cookie dict' but does not explain required fields (e.g., name, value, domain) or format, leaving the agent to guess the structure. It adds minimal meaning beyond the schema.

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 clearly states the action ('Add'), the resource ('Selenium cookie dict'), and the scope ('current domain'). It effectively distinguishes from sibling tools like delete_cookies and list_cookies.

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

Usage Guidelines3/5

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

The description implies usage (to add a cookie) but provides no explicit guidance on when to use this tool versus alternatives, nor when not to use it. No exclusions or prerequisites are mentioned.

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