list_available_signals

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

With no annotations, the description carries full burden. It transparently states that signal availability depends on the data source, and that absence from the list means unavailability. It also mentions the return includes units and typical ranges. It doesn't mention side effects or auth, but for a read-only list operation, this is sufficient and clear.

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 sentences: first states purpose, second gives usage guidance, third sets a rule. It is front-loaded with purpose and contains no extraneous information. Every sentence 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?

Given no output schema, the description adequately covers return format (list with units and ranges) and provides behavioral context for missing signals. The tool has no parameters, and the description is complete for its simple scope.

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 input schema has no parameters and schema coverage is 100%. The description adds value by confirming 'No parameters. Returns everything the current data source exposes,' and it specifies the return content (units and ranges) beyond the schema. Baseline 3 is exceeded due to extra context.

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 returns 'the complete list of signals available from the currently connected data source, with units and typical ranges.' It uses a specific verb ('list') and resource ('signals'), and the context distinguishes it from siblings like 'get_signal' which fetches specific signals.

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 explicitly advises: 'Call this FIRST whenever you are unsure whether a signal exists.' It provides clear rules: if a signal is not in the list, do not attempt to retrieve, estimate, or substitute, and inform the user of unavailability and the connected source. This offers excellent when-to-use and what-to-do guidance.

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