diff_first_divergence

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

With no annotations provided, the description carries the full burden of behavioral disclosure. It explicitly discloses the side effect (auto-registering a cursor for downstream reference) and the read-only nature ('Reads existing waveforms only — does NOT rerun simulation'). It doesn't mention edge-case behavior like 'no divergence found,' but the key behavioral traits are covered.

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?

Three sentences with no wasted words. The first sentence states the core function, the second gives use-case context, and the third addresses side effects and safety. All information is front-loaded and earns its place.

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?

The description covers the main behavior, use cases, and side effects, but since there is no output schema, the return value is not explicitly described. The agent can infer it likely returns a divergence time and/or cursor name, but the ambiguity around what happens when no divergence is found and what exact data is returned leaves a meaningful gap for a tool of this complexity.

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%, so the parameter semantics baseline is 3 even without additional explanation in the description. The description itself does not add parameter-level meaning, but the schema already documents all eight parameters, including formats for time values and cursor references.

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, unambiguous action: 'Find the first time two signals hold unequal values.' It then distinguishes two concrete use cases (across two waveforms, or within one waveform), which clearly separates it from sibling tools like get_signal_at_time or get_signal_transitions that inspect signals without diffing.

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?

The description provides clear context for when to use the tool, identifying both the cross-run and within-run comparison scenarios. It does not explicitly name alternatives or state when not to use it, but the two use-case patterns give the agent enough situational guidance.

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