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set_breakpoint

Set a breakpoint on an executable line to pause execution and inspect program state.

Instructions

Set a breakpoint. Setting breakpoints on non-executable lines (structural, declarative) may lead to unexpected behavior

Input Schema

TableJSON Schema
NameRequiredDescriptionDefault
sessionIdYes
fileYesPath to the source file or Java FQCN. For Java, passing a fully-qualified class name (e.g. "com.example.MyClass" or "com.example.Outer$Inner") is preferred — it works reliably with all classloaders including custom classloaders. Alternatively, use absolute file paths.
lineYesLine number where to set breakpoint. Executable statements (assignments, function calls, conditionals, returns) work best. Structural lines (function/class definitions), declarative lines (imports), or non-executable lines (comments, blank lines) may cause unexpected stepping behavior
conditionNo
suspendPolicyNoSuspend policy when breakpoint is hit: "all" suspends all threads (default), "thread" only suspends the event thread. Only supported by the Java/JDI adapter.
Behavior3/5

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

Without annotations, the description partially fulfills transparency by warning about unexpected behavior on non-executable lines, but omits other traits like side effects or session requirements.

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?

Two concise sentences, front-loaded with the purpose, no fluff. Every sentence serves a clear function.

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

Completeness3/5

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

The description covers the basic purpose and a key caution, but lacks details on conditional breakpoints, suspension policy, removal, and overall breakpoint lifecycle, which would be helpful given the tool's complexity and lack of output schema.

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 60%, with detailed descriptions for file and line. The description adds no new parameter-specific information beyond the warning about non-executable lines, which is already hinted in the line parameter description.

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 'Set a breakpoint.' clearly identifies the action and resource. The caveat about non-executable lines distinguishes it from other debug actions like step or evaluate.

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

Usage Guidelines2/5

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

No explicit when-to-use guidance or comparison to alternative tools (e.g., step_into). Only a caution about non-executable lines, which is minimal usage direction.

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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