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

With no annotations provided, the description fully carries the burden. It discloses that the tool shows live state (not forecast), that completion is not probability, direction is resemblance not odds, and that ARCANE never states likelihood. It also notes staleness and advises checking 'as_of/stale', which adds important behavioral context.

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 moderately lengthy but front-loaded with the core purpose. It contains some repetition (e.g., 'NOT a forecast' appears twice), but overall each sentence adds value. The structure is logical: purpose, details, then caveats.

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 tool has no parameters, no output schema, and no annotations. The description thoroughly covers what the tool returns and its semantics, including staleness, meaning of completion, direction, and what it does not provide. It is complete given the lack of other contextual fields.

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 schema has zero parameters, so there are no parameters to document. The description does not need to add parameter info. With no parameters, a baseline of 4 is appropriate, and the description adds rich semantics about the output.

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 it is a 'live scenario tracker' for pre-registered scenarios, detailing what it tracks: checkpoint completion as N/M, direction resemblance, staleness, and fork checkpoint status. It explicitly distinguishes itself from a forecast, which differentiates it from sibling tools like arcane_overview or arcane_deltas.

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 on when to use the tool (for tracking live state of pre-registered scenarios) and what it does not do (not a forecast, no probability). However, it does not explicitly mention when not to use it or directly compare with sibling tools, though siblings are listed in context.

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