timing_between

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

Annotations already indicate read-only, idempotent, non-destructive. The description adds behavioral details: it rejects AC analysis, explains threshold defaults (50% of each signal's range for asymmetric CMOS), picks only the first crossing, and defines signed delay. This fully informs the agent of behavior beyond annotations.

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 a single paragraph but well-organized: starts with purpose, then return value, threshold behavior, edge selection, and rejection. It is front-loaded with the most critical information and every sentence adds value without verbosity.

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 tool has an output schema, the description adequately covers return format and main behavior. It doesn't mention error conditions or edge cases like signals not found, but for a measurement tool with clear annotations and good parameter descriptions, it is sufficiently complete.

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 covers 83% of parameters with descriptions. The description adds contextual meaning: explains that threshold_pct is applied per signal, direction parameters can be set independently (e.g., rising input to falling output). While helpful, it doesn't add substantial new information beyond schema for most parameters.

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 clearly states the tool is for measuring propagation delay/skew between two signals, with specific examples like input-to-output delay and clock-to-Q. This differentiates it from sibling tools like edge_metrics or periodic_metrics that are for single-signal or repeated metrics.

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 explicit usage context: 'Use when you need propagation delay / skew between TWO signals'. It also details prerequisites (transient .raw with both signals on shared time axis) and gives advice for handling multiple edges (tighten window). This clearly guides when to use and how to use effectively.

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