Mark the current point in the network recording as the start of a flow, causing flow_export and flow_synthesize to capture calls recorded after this mark.
Mark the current point in the network recording as a flow's start. flow_export/flow_synthesize default their capture window to calls recorded after this mark.
| Name | Required | Description | Default |
|---|---|---|---|
| label | No | free-text note, echoed back in the confirmation | |
| sessionId | No |
Changes observed during successful MCP inspections.
v0.6.0Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
With no annotations, the description carries the full burden of behavioral disclosure. It explains a meaningful side effect on downstream tools, but does not disclose whether the mark is persistent, overwrites previous marks, or is scoped to a session.
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 two sentences with no filler. The core action is front-loaded, and the downstream effect is stated compactly in the second sentence.
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?
The core behavior is covered, but with no annotations and no output schema, the missing sessionId semantics and lack of detail about mark persistence or active-recording requirements leave some practical gaps for the agent.
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 50%: label has a description but sessionId does not. The tool description adds no parameter-level semantics, so sessionId remains opaque and the agent has to guess what it means.
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 uses a specific verb and resource: 'Mark the current point in the network recording as a flow's start.' It also distinguishes itself from related tools by explaining the relationship to flow_export and flow_synthesize, so an agent can tell exactly what this tool does.
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 description gives clear usage context: flow_export and flow_synthesize default their capture window to calls recorded after this mark, implying flow_mark should be called before those tools. It does not explicitly state when not to use it, but the context is sufficient for typical invocation.
Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.