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

Annotations already establish read-only, non-destructive, and idempotent behavior. The description adds the key behavioral fact of cost ('Cheapest call ($0.001)') and clarifies the return payload, which is useful beyond the structured 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?

A single sentence front-loads the most decision-relevant fact (cost) and then states the scope and returned fields. There is no filler or redundant restatement of the schema.

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 output schema, listing the headline fields is valuable and makes the return shape reasonably predictable. The main gaps are the un-explained 'window' parameter and the lack of explicit guidance about when to choose this over sibling tools, so it is not fully 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 description coverage is only 50%, and the description adds no meaningful parameter guidance—especially for 'window', which is left entirely to the schema enum. The listed fields are outputs, not parameter semantics, so the agent gains little beyond the schema for using the 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?

Description clearly identifies the tool as a low-cost, real-time single-symbol snapshot and enumerates the returned fields, which separates it from market-wide or historical tools. It lacks a direct verb and does not explicitly name sibling alternatives, but the resource and scope are specific.

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 '$0.001' cost and 'right now' imply the tool is for a cheap, immediate single-symbol check. It does not state when not to use it or name alternatives, so usage context is only implied, not explicit.

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