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

With no annotations, the description carries the full burden of behavioral disclosure. It adds the payment requirement ($0.005 per call via x402) which is a critical behavior beyond the basic intent. However, it lacks other behavioral details such as response format, error handling, or rate limits.

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 two short sentences, front-loaded with the core purpose and followed by the payment detail. Every word earns its place, with no redundancy or fluff.

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 simple one-parameter tool, the description covers the core purpose and cost. However, with no output schema, it does not describe the return format (e.g., list of game names, rankings, prices), which is a notable gap in completeness.

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 already provides a full description of the 'country' parameter ('ISO country code'), with 100% coverage. The tool description only adds 'by region,' which is consistent but does not add new semantic meaning. Baseline 3 is appropriate.

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 the tool's function: 'Current top-selling games on Steam by region.' This is a specific verb+resource+scope, and it distinguishes from siblings like steam_deals (deals) and game_metadata (metadata) by focusing on top-selling status.

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 provides clear context for what the tool returns, implying when to use it (to see top-selling games by region). However, it does not explicitly mention alternatives or exclusions, nor does it discuss trade-offs with sibling tools like steam_deals or steam_app_intel.

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