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

Annotations already cover read-only, idempotent and non-destructive. The description adds behavioral context those annotations cannot express: realtime data with an API key versus a delayed preview without one, which is an authentication and freshness constraint the agent needs. Rate limits and the exact preview delay are unstated, so not a 5.

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?

Two clauses separated by a semicolon, with the return scope front-loaded and the auth/freshness caveat second. Every sentence earns its place and nothing is repeated from the structured fields.

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?

With no parameters and no output schema, the description carries the whole burden, and it does say what comes back (label plus confidence) and how access affects freshness. The output's shape or possible label values are not described, which is a minor residual gap for a tool whose entire value is the returned label.

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 takes zero parameters, so per the rubric the baseline is 4. There is nothing for the description to disambiguate, and it correctly adds no parameter noise.

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 names a specific resource and scope: the *current* SPX dealer regime label plus its confidence, and explicitly rules out walls, gamma flip, net GEX and strike detail. That exclusion set distinguishes it from data-heavy siblings like get_market_structure and from the segment-oriented get_regime_segments without the agent opening any schema.

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 supplies a clear use case - 'a small read for checking whether conditions have changed' - and the exclusions imply when not to use it. It stops short of naming an alternative tool by name for the fuller picture, so it lands just below the top band.

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