Switch the active browser session so subsequent calls without an explicit session ID use it.
Switch the active session. Subsequent tool calls without an explicit sessionId will use this session.
| Name | Required | Description | Default |
|---|---|---|---|
| sessionId | Yes | Identifier of the session to switch to |
Changes observed during successful MCP inspections.
v0.1.0Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
Annotations declare readOnlyHint=false, destructiveHint=true, and openWorldHint=true, so the safety profile is partly covered. The description adds genuinely useful behavioral context beyond that: this tool mutates persistent state that affects all later calls lacking an explicit sessionId. It does not clarify whether the prior session is closed or whether invalid IDs error, so it stops at 4.
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?
Two short sentences, zero filler. The core action is front-loaded and the consequence follows immediately.
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 one-parameter tool with full schema coverage and annotations covering the safety profile, the description is close to sufficient: it explains the action and its lasting effect. It omits what happens to the previous session and error behavior on an unknown ID, which would round it out.
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% for the single parameter, so the schema already documents sessionId. The description adds functional meaning (this session becomes the default for later calls) but no format, validation, or error semantics, so baseline 3 applies.
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?
States a specific verb (Switch) and resource (active session), which is clearly distinct from the session_create, session_list, and session_close siblings. It doesn't explicitly name those siblings, so it falls just short of 5.
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 second sentence implies when this matters ('subsequent tool calls without an explicit sessionId'), which conveys the usage context. However, there is no explicit when-to-use / when-not-to-use guidance, no prerequisites, and no statement of what happens to the previously active session.
Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.