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

Annotations already declare readOnly, idempotent, non-destructive and closed-world. The description adds genuinely non-obvious behavioral context: it is 'Free' and 'one market day delayed', which tells the agent about cost and data freshness. It omits auth needs and rate limits, but for a read-only no-arg tool this is solid added value.

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?

Purpose is front-loaded in the first sentence, followed by return structure and then a freshness note. It is dense and slightly heavy on nested field detail, but every sentence carries information relevant to calling or interpreting the tool.

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, no output schema, and safety already covered by annotations, the description fills the main gap by describing the return payload (verdict, mode, permission ladder, posture components). It does not explain how to act on the verdict, but is largely complete for a zero-arg read tool.

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?

There are zero parameters, so the baseline is 4. The schema accepts no arguments, and the description correctly focuses on the return shape rather than fabricating input semantics.

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?

States a specific verb and resource ('top-down stock market regime read'), enumerates the verdicts (risk-on, be-selective, stand-down), and lists exactly what it returns (verdict, mode, permission ladder, posture per book). The closing note that data is one market day delayed implicitly distinguishes it from the get_market_regime_live sibling.

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 'top-down' framing and 'one market day delayed' note imply usage versus live siblings, but there is no explicit when-to-use/when-not statement or named alternative. The agent must infer that get_market_regime_live should be preferred for real-time reads.

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