js-reverse-mcp

by zhangjia2024

Overview Schema Source Related Servers Discussions Admin

step

Advance paused JavaScript execution by one debugger operation and return the next stopped call frame with concise source context.

Instructions

Advances JavaScript execution by one debugger operation from an existing pause and returns the next stopped call frame with concise source context. Use after get_paused_info or evaluate_script when control flow still needs tracing; it cannot start from running execution. Each advance invalidates prior callFrameIds, so inspect the new pause again as needed, then use pause_or_resume(action="resume") to finish.

Input Schema

Name	Required	Description	Default
`direction`	Yes	Choose "over" for the next statement without entering calls, "into" to follow a call, or "out" to continue until the current function returns.

Output Schema

Name	Required	Description
`ok`	Yes	Whether the tool completed successfully.
`data`	No	Machine-readable result payload.
`tool`	Yes	Stable MCP tool name.
`error`	No
`summary`	Yes	Concise human-readable outcome.

Schema Changelog

Changes observed during successful MCP inspections.

First observedv4.0.5Oct 25, 2026

TDQS

A4.7/5.0

Behavior5/5

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

Annotations indicate readOnlyHint=false and destructiveHint=false. The description adds critical behavioral details: invalidates prior callFrameIds, requires existing pause, and returns next call frame. No contradiction with annotations.

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?

Description is efficient and front-loaded with the main action. Three sentences cover behavior, prerequisites, and follow-up without fluff. Every sentence adds value.

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?

Given full parameter schema, annotations, and output schema, the description is complete. It covers prerequisites, invalidation, and next steps, leaving no gaps for an agent.

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% with descriptions for the direction parameter. The tool description does not add extra meaning beyond the schema, so 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?

The description clearly states it advances JavaScript execution by one debugger operation from a pause, with a specific verb and resource. It distinguishes from siblings like pause_or_resume and get_paused_info by specifying its role in tracing control flow.

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?

Explicitly says to use after get_paused_info or evaluate_script when control flow needs tracing, and not from running execution. Also directs to use pause_or_resume to finish, providing clear context and alternatives.

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