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

Annotations already declare readOnlyHint=true, openWorldHint=true, idempotentHint=true, and destructiveHint=false, so the safety profile is covered. The description adds valuable behavioral context beyond that: recomputation cadence (~every 10s during market hours), the realtime-vs-delayed data split, and the 'Data only -- not investment advice' disclaimer. It does not fully detail the output shape, but with no output schema and a rich payload, the description carries a heavy burden and mostly meets it.

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 a single dense block that front-loads the core resource and then lists many components. It is information-dense but somewhat run-on, with a long comma-separated enumeration that could be structured into clearer sentences or bullets. Every sentence earns its place, but the wall-of-text format reduces scannability for an agent.

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?

For a zero-parameter, read-only data tool with no output schema, the description is quite complete: it names the data categories, the refresh cadence, the auth requirement, the degraded mode without a key, and the non-advice disclaimer. The main gap is that it does not specify the exact response format or field names, but the description's enumeration largely compensates for the missing output schema.

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 there is no parameter semantics burden on the description. The schema already documents an empty object with additionalProperties=false. The description's detailed enumeration of what the response contains compensates for the lack of an output schema, effectively telling the agent what data it will receive without needing parameters.

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 opens with a specific verb ('get') and a precise resource ('current computed SPX dealer market structure'), then enumerates the concrete components (walls, gamma flip, net GEX, regime, strike ladder, forecast bands, etc.). It clearly distinguishes itself from siblings like get_regime and get_day by naming the full market-structure payload rather than a single regime or day snapshot.

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 explicitly states when realtime data is available (requires a funded X-API-Key) and what happens without a key (delayed headline preview only). It also names the exact place to create a key. This gives an agent clear go/no-go conditions and distinguishes the realtime vs preview behavior, which is more actionable than most sibling-routing guidance.

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