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

Annotations already indicate read-only and idempotent behavior. The description adds valuable context beyond that: the FREE vs HOBBY+ tier restriction, the history boolean parameter behavior, and the 'empirical next-day transition odds' detail. This gives a richer picture of what the tool returns and under what conditions, without contradicting annotations.

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 compact and well-organized: one sentence catalogs the analytics, and a second sentence explains tiered access. No wasted words; every phrase earns its place. The structure is front-loaded with the defining purpose before procedural details.

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 a single simple parameter, an output schema, and no nested objects. The description covers what data is returned, the tier constraints, and the history option. For a read-only analytics tool, this is sufficiently complete.

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?

Schema coverage is 100% with the history parameter already described. The description adds the contrast between FREE (today's reading) and HOBBY+ (history) and explicitly mentions 'pass history=true', which clarifies the parameter's effect in context. This goes slightly beyond the schema by tying the parameter to the tier system.

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 provides whole-universe derived market analytics, enumerating the specific metrics (factor dispersion, breadth, SPY-volatility regime). This differentiates it from siblings like get_market_regime and get_vx_term_structure, which focus on other aspects. The scope and content are explicit.

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 gives clear context on what the tool does and includes tier-based guidance: FREE gets today's reading, HOBBY+ can also get history. It doesn't explicitly compare to alternatives, but the unique metrics make the intended use clear. No exclusions or alternative tools are named, so it misses the top score.

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