debug_compare_runs

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

The description adds meaningful behavioral context beyond the readOnly/idempotent/non-destructive annotations: it discloses that comparison is semantic, that stack/locals/registers/exception/symbol/module evidence is compared, and that 'non-null raw address-only changes are marked unstable rather than causal evidence.' This tells the agent how results should be interpreted and reinforces that the tool observes rather than mutates sessions.

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 three focused sentences. The first states purpose, the second gives usage context and the comparative scope, and the third provides an exclusion and directs preparation. Every sentence earns its place with no repetition of schema or annotation content.

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?

Given the rich input schema, output schema, and annotations, this description is complete for safe and correct invocation. It covers when to use, what is compared, how unstable address-only changes are treated, and what the tool must not be used for. No critical operational knowledge is missing.

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 description coverage is 100%, with both required session parameters and the nested snapshot object clearly documented. The prose description adds contextual framing but does not materially expand on the parameter meaning already present in the schema, so it stays at the baseline for high-coverage schemas.

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 opens with a specific verb and resource: 'Compare bounded runtime evidence from two existing stopped DAP sessions.' It then distinguishes the tool from single-session diagnostics by framing it for 'baseline or known-good versus candidate or failing differential debugging,' which cleanly separates it from sibling tools like debug_snapshot and debug_diagnose_stop.

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?

It explicitly states when to use the tool: for differential debugging 'after both sessions have reached comparable stops.' It also gives clear when-not guidance: 'Do not use it to launch, resume, or alter either target; prepare both runtime states with the normal lifecycle tools first.' This directs the agent to alternative lifecycle tooling without ambiguity.

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