list_signals

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

With no annotations provided, the description carries the full transparency burden. It explicitly states 'No side effects' (read-only behavior), discloses output details (current aspect and 'lit' status), and gives a usage warning about validating aspects before set_signal. This is strong behavioral disclosure.

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 concise sentences, front-loaded with the core purpose. Every sentence adds value: first defines the function, second gives usage guidance, third provides cross-tool context. No redundancy or fluff.

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?

For a simple no-param list tool, the description is complete. It covers what the tool does, when to use it, that it has no side effects, what output fields to expect (aspect, lit), and how to follow up with related tools. Nothing essential 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?

The tool has zero parameters, so the baseline is 4 per the rubric. The description adds no parameter details (none needed) but does illuminate output semantics, which is helpful. No deductions necessary; it fully meets the baseline.

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+resource: 'List every signal mast known to JMRI, with its current aspect.' It clearly distinguishes its scope (all masts, with aspects) from related sibling tools like get_signal, set_signal, and list_signal_aspects by explicitly pointing to those alternatives.

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 provides explicit when-to-use guidance: 'Use to discover what signal masts exist, or answer "what signals are there?"...' and even directs to alternative tools for related tasks (signal_off for darkening, list_signal_aspects before set_signal). This fully addresses usage context and alternative selection.

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