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web_session_close

Idempotent

Closes the browser session and stops its time. HTTP equivalent: POST /web/v1/session/{id}/close. No additional close fee; outstanding browser time is settled when applicable. If you do not close it, it closes itself after a minute without use.

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": {
      "sessionId": "<sessionId>"
    },
    "name": "web_session_close"
  }
}

Input Schema

Name	Required	Description	Default
`sessionId`	Yes	The session to close, from web_session_open.

Schema Changelog

Changes observed during successful MCP inspections.

Changed1 schema field changedOct 4, 2026
- addedInput schema / properties / sessionId / description
```
Added value: +"The session to close, from web_session_open."
```
First observedSep 29, 2026

TDQS

A4.1/5.0

Behavior4/5

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

Annotations already declare destructiveHint=false and idempotentHint=true, so the safety profile is covered. The description adds non-obvious behavior: billing semantics ('No additional close fee; outstanding browser time is settled') and the idle auto-close timeout, which an agent cannot infer from structured fields.

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?

Four short sentences, front-loaded with the action, with no padding. The HTTP-equivalent line is mildly extraneous for a chat agent but is compact and occasionally useful.

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?

For a one-parameter lifecycle tool with no output schema and annotations already covering safety, the description supplies billing, idle-timeout, and endpoint context. It does not state the return shape, but with no output schema that is a minor gap.

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 description coverage is 100%, so the single sessionId parameter is already documented in the schema as coming 'from web_session_open.' The description adds no syntax or format detail beyond that, so the baseline 3 applies.

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 ('Closes the browser session') that pairs cleanly with the sibling web_session_open, and the schema reference back to 'web_session_open' reinforces the lifecycle pairing. An agent can tell exactly what this does without opening the schema.

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?

It gives implicit when-to-use guidance by noting the session 'closes itself after a minute without use,' which tells the agent closing is optional and only needed for immediate teardown. It does not name an explicit alternative or exclusion, but the auto-close caveat is real routing context.

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

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