Retrieve a single cookie by its name from the active browser session, returning null when it doesn't exist.
Get a single cookie by name. Returns null if not present.
| Name | Required | Description | Default |
|---|---|---|---|
| name | Yes | Cookie name to get. |
Changes observed during successful MCP inspections.
v1.1.0Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
With no annotations provided, the description bears the behavioral transparency burden. It usefully discloses the null return when the cookie is absent, which is informative. However, it does not explicitly state whether the operation has side effects or any access constraints, though 'Get' implies a read-only action.
Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.
Is the description appropriately sized, front-loaded, and free of redundancy?
The description is two short sentences with no filler. The primary action is front-loaded and the return behavior is stated efficiently. Every word contributes value.
Shorter descriptions cost fewer tokens and are easier for agents to parse. Every sentence should earn its place.
Given the tool's complexity, does the description cover enough for an agent to succeed on first attempt?
For a simple one-parameter getter with no output schema, the description is nearly complete: it states the action, the selection criterion, and the return behavior. A small gap is not mentioning cookie scoping or that this only reads from the current context, but that is minor for this tool's simplicity.
Complex tools with many parameters or behaviors need more documentation. Simple tools need less. This dimension scales expectations accordingly.
Does the description clarify parameter syntax, constraints, interactions, or defaults beyond what the schema provides?
Schema description coverage is 100%, so the schema already documents the 'name' parameter. The description adds minimal additional meaning by indicating the cookie is selected by name, but it does not substantially expand beyond the schema.
Input schemas describe structure but not intent. Descriptions should explain non-obvious parameter relationships and valid value ranges.
Does the description clearly state what the tool does and how it differs from similar tools?
The description explicitly states the verb 'Get', the resource ('single cookie'), and the selection method ('by name'), which clearly distinguishes it from sibling tools like browser_cookie_list. It also specifies the return behavior, making its purpose unambiguous.
Agents choose between tools based on descriptions. A clear purpose with a specific verb and resource helps agents select the right tool.
Does the description explain when to use this tool, when not to, or what alternatives exist?
The phrase 'single cookie by name' gives clear context for when to use this tool: when you need one specific cookie rather than listing all cookies. It does not explicitly mention alternatives, but the intent is clear enough for an agent to route correctly.
Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.