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

With no annotations, the description carries the full behavioral burden. It discloses the cost behavior (billing at x402 price for live components) and the free tier for delayed samples, which is essential for an agent to avoid surprise costs. However, it does not mention rate limits, authentication, or any side effects, leaving some gaps.

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 moderately long but every sentence serves a purpose: it covers pricing, scope meanings, and usage guidance in a structured way. The information is front-loaded with the pricing note, which is critical for decision-making.

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 single-parameter tool with no output schema, the description provides sufficient context: it explains the three scopes, pricing, and when to use it. It lacks details on return format, but that is not required without an output schema, and the description is otherwise comprehensive.

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 schema only says 'Which area to snapshot,' but the description elaborates each enum value with what it returns (e.g., 'brazil' returns central-bank macro, real interest rate, Ibovespa, and B3 blue chips). This adds substantial semantic value beyond the schema, helping the agent choose the right scope.

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 that this tool provides a broad market snapshot across three scopes (brazil, global, crypto), distinguishing it from tools that return a single number. It uses a specific verb ('snapshot') and resource ('market'), and the scope enumeration gives concrete examples of what each returns.

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 explicitly instructs to use this when the question is broad rather than about one number, and notes the pricing difference (free for delayed samples, billed for live components). This gives clear guidance on when to prefer this tool over alternatives that might focus on specific data points.

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