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save_state

Export the current session (cookies + localStorage) to a Playwright storageState JSON at path — a portable, reusable authenticated session.

Instructions

Export the current session (cookies + localStorage) to a Playwright storageState JSON at path — a portable, reusable authenticated session.

Set for_chromium=True when a Chromium tool such as agent-browser will load the file (agent-browser --state <path>). Non-secure SameSite=None cookies then become Lax, which Chromium accepts.

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": {
      "path": "<path>"
    },
    "name": "save_state"
  }
}

Input Schema

Name	Required	Description	Default
`path`	Yes
`for_chromium`	No

Output Schema

Name	Required	Description	Default
`result`	Yes

Schema Changelog

Changes observed during successful MCP inspections.

Changed1 schema field changedv0.16.1Oct 23, 2026

addedInput schema / properties / for_chromium

Added value: +{
+  "default": false,
+  "title": "For Chromium",
+  "type": "boolean"
+}

Addedv0.4.0Sep 3, 2026

TDQS

A4.4/5.0

Behavior4/5

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

With no annotations, the description carries the full load and does disclose a non-obvious behavioral trait: non-secure SameSite=None cookies are rewritten to Lax when for_chromium is used. It does not say whether an existing file at path is overwritten, whether the path must exist, or what errors can occur, which are meaningful gaps for a file-writing tool.

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?

Two short paragraphs, front-loaded with the core action, and every sentence adds information — the second paragraph exists solely to explain the one non-obvious flag. No filler or repetition of the schema.

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

Completeness4/5

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, and the two-parameter surface is covered. The remaining gap is failure/overwrite behavior for the destination file, which matters for a tool that writes to a caller-supplied path.

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

Parameters4/5

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

Schema coverage is 0%, so the description must supply parameter meaning and largely does: path is where the storageState JSON is written, and for_chromium is tied to Chromium consumers with the cookie-rewrite consequence explained. It adds real semantics beyond the bare schema, though it does not clarify whether path is absolute or relative.

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?

States a specific verb and resource: 'Export the current session (cookies + localStorage) to a Playwright storageState JSON'. The output format and portability purpose are made explicit, so an agent knows exactly what artifact this produces and that no sibling tool does the same.

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

Usage Guidelines4/5

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

Gives a clear conditional: set for_chromium=True when a Chromium tool such as agent-browser will load the file. That is real routing guidance, but the description never states the general when-to-use condition (e.g., before handing a session to another browser tool) or any exclusion, so it stops short of full when/when-not coverage.

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