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

With no annotations, the description carries the full burden, and it does well by describing the output summary fields (current rate, mean, annualised mean, extremes, positive/negative periods, paying side) and the hourly cadence. It does not mention read-only status or default parameter behavior, but for a data-query tool the disclosed return content is the key behavioral trait.

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 sized and front-loads the core purpose before adding domain context and sibling routing. The sentence about funding being the main cost of holding a position is useful context, not filler, though the description could be tightened slightly.

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 5-parameter tool with no output schema and no annotations, the description explains the return summary but omits parameter semantics, required combinations, and any defaults. It helps an agent understand what the tool returns, but not fully how to parameterize it reliably.

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 adds limited param meaning by noting 'hourly' and 'one Polymarket Perps market', but it does not clarify how id, symbol, and instrument relate, what hours/limit units are, or how optional parameters combine. The generic schema descriptions are not enriched enough.

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 states a specific verb and resource: it retrieves 'Funding-rate history for one Polymarket Perps market, hourly' and lists the exact summary fields it returns. It also names the sibling tool x402-perp-funding-arb, making it easy to distinguish this tool from a related comparison tool.

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 clearly says to pair this tool with x402-perp-funding-arb to compare the same asset against Hyperliquid, giving explicit usage context. It does not enumerate all alternative tools or provide direct 'when not to use' exclusions, but the main routing guidance is present.

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