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

Adds substantial operational context beyond the read-only/open-world annotations: no API key required, empty-result meaning, interval-to-spacing behavior, evenly sampled maxPoints with first and last kept, and raw pointCount. This is exactly the kind of behavior an agent needs before calling the tool.

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 dense but front-loaded paragraph: purpose and core caveats come first, and each sentence carries unique operational information without padding. It is appropriately sized for the number of gotchas the tool has.

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 4-parameter read-only tool with an output schema and annotations, the description covers the key agent-facing details: outcome selection, point scale, venue support, empty-result meaning, sampling, and auth. Nothing essential to correct invocation appears missing.

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 coverage is 100%, so the baseline is 3. The description meaningfully extends the schema by clarifying that interval is a lookback range with venue-chosen spacing and that maxPoints controls even sampling with endpoints kept, adding practical semantics beyond the field descriptions.

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?

Names a specific resource and outcome scope: price history for ONE outcome, selecting the Yes leg of a binary market or the first live outcome. It does not explicitly name or differentiate from sibling price/volume tools, so it falls short of the 5-level sibling routing.

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?

Provides a clear when-not condition: Polymarket and Kalshi are supported, and other venues return an empty points array meaning not served here. It does not name alternative sibling tools for related needs, so it lacks the explicit alternative routing of a 5.

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