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

Annotations already declare readOnlyHint, idempotentHint, openWorldHint, and destructiveHint=false. The description adds important context beyond annotations: the $0.75/call cost and HTTP 402/MPP payment requirement, plus the nature of the signal as measured lead/lag evidence with invalidation logic.

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?

Three short sentences with zero waste. Paid cost is front-loaded, the purpose follows immediately, and the payment protocol closes the description, making it easy to parse.

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 that an output schema exists and annotations cover safety behavior, the description is largely complete for a zero-parameter tool. The main gap is not addressing when to choose this paid signal over the free preview or other siblings, but the core invocation-relevant details are present.

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 the baseline is 4. The description does not need to explain parameter meaning, and it does not introduce any confusion about inputs.

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 states a specific resource: global directional market intelligence with measured lead/lag evidence and explicit invalidation logic. It clearly signals what the tool returns, but it does not explicitly differentiate this signal from siblings like shadowgraph_global_snapshot or shadowgraph_alpha.

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 no guidance on when to use this tool versus alternatives such as shadowgraph_free_preview or shadowgraph_alpha. It only states the cost and payment mechanism, leaving the agent to infer usage conditions.

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