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

Annotations already declare readOnlyHint=true, openWorldHint=false, destructiveHint=false, so the safety profile is covered. The description adds genuinely new behavioral context: this tool returns bare numbers with no interpretation, and it lists the three values produced. It does not discuss defaults for the optional intervalHours/transferFeePct or edge cases like negative rates, so it stops short of a 5.

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?

Front-loads the computation and its outputs, then routes to the sibling, then gives trigger phrasings — good ordering. The trailing 'Returns: netProfitUsdt, annualizedYieldPct, breakevenDays' partially repeats the opening sentence's output list, which is the only mild redundancy.

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, the description correctly compensates by naming the returned fields, and the input schema fully covers all six parameters. What is missing is guidance on optional-parameter defaults and behavior on unusual inputs, but for this calculation tool an agent has enough to call it correctly.

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 100%, including the enum for intervalHours and the positive/negative sign convention for both funding rates, so the schema carries the parameter burden. The description adds no syntax, units, or defaults beyond what is already documented, making the baseline 3 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?

States a specific verb and resource ('Calculate funding rate arbitrage profit: annualized yield, net profit, and breakeven days for a long/short basis trade across two exchanges') and explicitly names the sibling it is not (run_carry_trade). An agent can separate it from run_funding_breakeven, run_compound_funding, and run_cross_venue_arbitrage without opening a schema.

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?

Names the alternative tool and the exact condition that selects it ('For the same math plus a profitable/marginal/loss verdict, use workflow.run_carry_trade instead'), and gives concrete user phrasings that should route here. When-to-use, when-not-to-use, and the alternative are all explicit.

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