Retrieves a browser localStorage value by key, returning null if the key doesn't exist. Provides direct access to client-side data for automated web workflows.
Get a localStorage item by key. Returns null if absent.
| Name | Required | Description | Default |
|---|---|---|---|
| key | Yes |
Changes observed during successful MCP inspections.
v1.1.0Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
With no annotations, the description carries the behavioral burden. It usefully discloses that the tool 'Returns null if absent', which is valuable edge-case behavior. However, it does not state that the operation is read-only, side-effect-free, or scoped to the current page origin, leaving some behavioral context implicit.
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 a single, efficiently worded sentence that front-loads the action and resource. It includes the most important behavioral note (null return) without any wasted words.
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 read operation with no output schema, the description is largely complete: it states the operation, the input, and a key return behavior. Minor context about storage scope or read-only safety could strengthen it, but the low complexity makes the current description nearly sufficient.
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 coverage is 0%, so the description must give the parameter meaning. It does so minimally by explaining that the 'key' identifies the localStorage item to retrieve. This is enough for a single self-explanatory parameter, but no additional detail such as key format or behavior for empty strings is provided.
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 clearly states the action ('Get'), the resource ('localStorage item'), and the selection mechanism ('by key'), making the tool's purpose immediately understandable. It does not explicitly differentiate itself from siblings like browser_localstorage_list, but the phrasing makes the distinction obvious.
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?
No guidance is provided about when to use this tool versus alternatives such as browser_localstorage_list, browser_localstorage_set, or browser_sessionstorage_get. The description implies a simple key lookup but offers no context on prerequisites or exclusions.
Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.