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

Annotations already declare readOnlyHint=true and destructiveHint=false, indicating a safe read operation. The description adds valuable context: it is free, public, and requires no API key. It also explains the data's purpose and comparability. No contradictions with 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?

The description is extremely concise: two sentences that front-load the primary function and follow with usage guidance. Every word adds value, and it avoids redundancy with the schema or annotations.

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 the presence of an output schema, the description need not explain return values. It provides a complete picture: what data is returned, when to use it (before comparisons), and constraints (free, no key). The sibling tools are numerous, but this description sufficiently distinguishes its role.

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 input schema has a single parameter 'fiat' with a description in the schema itself, achieving 100% coverage. The tool description does not add new information about this parameter, so it meets the baseline of 3. It does not detract but does not enhance beyond the schema.

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 identifies the tool as providing free public methodology and comparable coverage for each prediction-market venue, listing specific data elements (source kind, metrics, volume bases, etc.). It distinguishes itself from sibling tools by focusing on comparability and methodology, addressing the need before comparing venue totals.

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 to use the tool: 'Use this before comparing venue totals so a completed-day figure is never described as rolling 24h and play-money points are never described as USD.' It also mentions no API key required, implying ease of use. However, it does not explicitly exclude other scenarios or name alternative tools, which would elevate the score.

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