Browser Session MCP

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delete_browser_state

DestructiveIdempotent

Permanently delete a saved browser state by name to forget a stale or unwanted login. Open sessions keep their cookies; repeat deletions are safe.

Instructions

Delete a saved browser state by name, permanently; open sessions that already loaded it keep their cookies. Use it to forget a login that is stale or no longer wanted; to update a state, call save_browser_state with the same name instead. Use list_browser_states to see the names. Deleting a name that doesn't exist succeeds with removed false, so it is safe to repeat.

Input Schema

Name	Required	Description	Default
`name`	Yes	Name of the saved state: letters, digits, '.', '_' and '-' only.

Output Schema

Name	Required	Description	Default
`name`	Yes
`removed`	Yes	False if no state had that name.

Schema Changelog

Changes observed during successful MCP inspections.

Changed1 schema field changedv0.1.5Oct 24, 2026

changedOutput schema / (root)

Previous value: -nullNew value: +{
+  "$schema": "https://json-schema.org/draft/2020-12/schema",
+  "properties": {
+    "name": {
+      "type": "string"
+    },
+    "removed": {
+      "description": "False if no state had that name.",
+      "type": "boolean"
+    }
+  },
+  "required": [
+    "name",
+    "removed"
+  ],
+  "type": "object"
+}

Changed1 schema field changedOct 23, 2026
- addedInput schema / properties / name / description
```
Added value: +"Name of the saved state: letters, digits, '.', '_' and '-' only."
```
First observedv0.1.2Oct 23, 2026

TDQS

A4.7/5.0

Behavior5/5

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

Goes well beyond the annotations, which only flag destructive=true and idempotent=true. The description adds the non-obvious operational nuance that already-open sessions keep their cookies, and explains the idempotent behavior concretely (missing name returns removed false), which is exactly the context an agent needs before repeating a destructive call.

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?

Four tight sentences, each carrying distinct information: what it does, why to use it, the alternative, and the repeat-safety caveat. The destructive scope is front-loaded before any advisory content.

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

Completeness5/5

Given the tool's complexity, does the description cover enough for an agent to succeed on first attempt?

For a single-parameter destructive tool with full schema coverage, a rich annotation set, and an output schema, nothing material is left out. The description even pre-explains the removed=false return case, which is more than the output schema alone would guarantee an agent notices.

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

Parameters3/5

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

Schema coverage is 100% and the schema already documents the allowed character set for `name`, so the description adds little syntax detail. It does supply the semantic pointer that names come from list_browser_states, but that is contextual rather than parameter-level elucidation; baseline 3 is appropriate.

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?

Opens with a specific verb+resource+scope: "Delete a saved browser state by name, permanently." It actively disambiguates from the closest siblings by name (save_browser_state for updates, list_browser_states for discovery), so an agent can pick it without opening any schema.

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

Usage Guidelines5/5

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

States the use case ("forget a login that is stale or no longer wanted"), the explicit alternative for the adjacent intent ("to update a state, call save_browser_state with the same name instead"), and how to find valid inputs (list_browser_states). When-to-use and when-to-use-something-else are both covered.

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