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

With no annotations, the description carries full responsibility. It warns that 'some senses go silent when their baseline saturates' and advises checking staleness, providing useful behavioral context beyond a simple data retrieval. It does not mention auth or rate limits, but these are less critical for a read-only tool.

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 concise (two sentences), front-loaded with key information ('Latest observations'), and every sentence adds value. No wasted words.

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 parameters, no output schema, and moderate complexity, the description covers what the tool returns, the caveat of silent saturation, and hints at freshness. It could be more detailed about data format, but it is adequate for the tool's simplicity.

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 baseline is 4. The description does not need to add parameter information since there are none, and it already explains what the data contains.

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 that the tool provides 'Latest observations from ARCANE's primary-source physical senses' and lists examples like energy stocks, fires, sanctions, etc. It distinguishes itself from sibling tools which have different names and presumably different purposes (e.g., arcane_bilateral, 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 implies usage for retrieving observed levels from physical senses and mentions checking freshness ('Check as_of/stale'), but it does not provide explicit guidance on when to use this tool versus alternative sibling tools, nor does it state when not to use it.

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