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set_breakpoint

Set breakpoints at specific code lines to pause execution and inspect application state, with optional conditional expressions for precise debugging.

Instructions

Sets a breakpoint at a specific location in the code. The breakpoint will pause execution when the specified line is reached. You can set conditional breakpoints that only trigger when an expression evaluates to true.

Input Schema

TableJSON Schema
NameRequiredDescriptionDefault
session_idYesID of the debugging session.
urlYesURL of the script where the breakpoint should be set. For Node.js, use file:// URLs (e.g., file:///path/to/script.js). For remote scripts, use the full URL. Use list_scripts to find available scripts.
line_numberYesLine number (0-based) where the breakpoint should be set. Note: Most editors display 1-based line numbers, so subtract 1.
column_numberNoOptional column number (0-based). Useful for setting breakpoints in minified code.
conditionNoOptional JavaScript expression. The breakpoint only triggers when this expression evaluates to true. Example: "count > 100" or "user.name === 'admin'"
Behavior2/5

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

No annotations provided, so description should fully disclose behavioral traits. It only states that breakpoints pause execution, but omits details like performance impact, persistence, maximum breakpoints, or behavior on invalid session/url.

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?

Extremely concise at two sentences, no wasted words. Front-loaded with the core action and behavior.

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

Completeness2/5

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

Given the complexity of five parameters and no output schema, the description lacks crucial context such as error handling, expected return value or confirmation, interaction with other breakpoint tools, and edge cases like duplicate breakpoints or invalid line numbers.

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% and each parameter is well-documented in the schema. The description adds the concept of conditional breakpoints, but the condition parameter is already explained in schema. Baseline 3 applies due to high schema coverage.

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?

Clearly states the tool sets a breakpoint at a specific location (url and line number) and mentions conditional breakpoints. Distinguishes clearly from sibling tools like remove_breakpoint or list_breakpoints.

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

Usage Guidelines3/5

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

Implies usage for debugging but lacks explicit guidance on when to use this tool versus other breakpoint-related tools (e.g., set_pause_on_exceptions) or when not to use it. No mention of prerequisites or alternatives.

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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