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pwndbg_top_chunk

Displays information about the top chunk (wilderness) in a heap arena, used to service allocations when no suitable freed chunk is available.

Instructions

Print information about the top chunk (wilderness) of an arena.

pwndbg command: top_chunk Source: pwndbg/commands/ptmalloc2.py Category: GLibc ptmalloc2 Heap

The top chunk is the last chunk in the heap, used to service allocations when no suitable freed chunk is available.

Args: session_id: The UUID of the session. addr: Optional arena address.

See: https://pwndbg.re/2025.05.30/reference/pwndbg/commands/ptmalloc2/

Input Schema

TableJSON Schema
NameRequiredDescriptionDefault
session_idYes
addrNo

Output Schema

TableJSON Schema
NameRequiredDescriptionDefault
resultYes
Behavior2/5

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

No annotations are provided, and the description only states 'print information' without disclosing side effects, permissions, or state requirements. For a tool that may read memory, more disclosure is needed.

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?

Front-loaded with a clear one-line purpose, followed by background and parameter list. Every sentence adds value without redundancy.

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

Completeness4/5

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

Covers purpose and basic usage; output schema exists so return is not needed. Missing prerequisites like needing a running debug session, but sufficient for an informational command.

Complex tools with many parameters or behaviors need more documentation. Simple tools need less. This dimension scales expectations accordingly.

Parameters4/5

Does the description clarify parameter syntax, constraints, interactions, or defaults beyond what the schema provides?

The description adds an 'Args' section explaining session_id as UUID and addr as optional arena address, which goes beyond the schema titles. However, it lacks format or constraints.

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?

Specifies verb 'print information' and resource 'top chunk of an arena', clearly distinguishes from heap siblings like pwndbg_malloc_chunk or pwndbg_bins.

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

Usage Guidelines4/5

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

Provides context that top chunk is the wilderness used for allocations, but does not explicitly state when not to use or list alternative commands for similar heap inspection.

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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